


Fistbump (a Pinecest Story)

by Edward_or_Ford



Series: Fistbump AU [1]
Category: Gravity Falls
Genre: F/M, Sibling Incest, pinecest - Freeform
Language: English
Status: Completed
Published: 2016-05-11
Updated: 2016-05-20
Packaged: 2018-06-07 15:54:39
Rating: Explicit
Warnings: Underage
Chapters: 10
Words: 28,238
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/6812140
Author URL: https://archiveofourown.org/users/Edward_or_Ford/pseuds/Edward_or_Ford
Summary: <blockquote class="userstuff">
              <p>Dipper and Mabel, their fourteenth birthday celebration in the city, and the fallout.</p>
            </blockquote>





	1. Beg, Shame, and Extort

**Author's Note:**

> So, this was my first stab at writing a Pinecest fanfic. Actually, this was my first fanfic of any kind. To be completely honest, this was the first creative writing of any kind that I’ve done since high school, a quarter century ago. Wow, way to set your expectations for me at the low end of the scale.
> 
> Yet somehow, I believe this actually turned out pretty good! I think Pinecest shippers will appreciate it.
> 
> Some stray points:
> 
> \- It’s a bit of a beast, over 28,000 words, but I tried to keep it moving along.  
> \- I’ve portrayed them fairly young, as the story takes place as they celebrate their fourteenth birthday by themselves in the city. Their immaturity and inexperience plays a part in the narrative, and I tried to realistically represent what could happen in the situation they found themselves in.  
> \- The story is not “crass”. It is an explicit story of young love, hopefully written somewhat tastefully. But yes, this is about incest between kids fresh out of middle school, and they are going to do the nasty. If that offends you, stop now.  
> \- I tried very hard to represent the characters of Mabel and Dipper, but I will readily admit that I can’t quite channel enough goofiness for Mabel. I did my best on the comedy side, but if you’re preparing for disappointment, I’d start there. Sorry in advance.  
> \- There’s a fair amount of accurate “real world” detail. All the places I reference in the city of Portland are genuine.  
> \- I wrote this story in early 2015, so some details revealed at the end of the series are not correctly depicted here. Namely, in my story I made the following educated guesses (that were incorrect):  
> \---> Stanley is still running the Mystery Shack  
> \---> Soos is still just an employee  
> \---> Stanford is no longer in the picture  
> \---> Dipper and Pacifica had a brief romantic moment before the end of their first summer  
> \---> there is a week between the twins' birthday and the last day of summer vacation
> 
> So, with that out of the way, I hope you enjoy the story!

* * *

 

“Come on, Grunkle Stan!” whined Mabel, chasing after her great-uncle as he walked toward the cash register in the Mystery Shack.

“Yeah, come on! We just want you to think about it!” added Dipper.

Stan turned around, exasperated. He waved his arms around and gestured to the building, having just locked up for the evening minutes before. “What? You think I can afford to close the Shack on one of the last weekends of the summer? So that I can hang around and watch you two spend all your money on a stupid trip to the city? Forget it!”

Dipper and Mabel looked at each other. This was not going as well as expected. They had hoped that their uncle would think their idea was perfectly reasonable, but their plans for a grand birthday celebration, in a couple of weeks, were now on the verge of collapse. They were about to turn fourteen: their birthday was on the last Saturday of August, the weekend before the Pines twins were due to finish their summer vacation in Gravity Falls, Oregon.

“Vacation,” of course, is another word for “labor” when it comes to staying at their great-uncle’s tourist-trap home. For the past two summers, Grunkle Stan had put them to work, making sure that the creepy trinkets and strange displays were to the idiot visitors’ liking. But they had actually done well in the Shack, and their uncle had grumbled reluctantly that business the previous year had been good, and had been particularly great that current summer.

The last summer, of course, had been the weirdest summer ever. The twins arrived as twelve-year-old innocent tweens, and were immediately thrust into adventure after misadventure, facing terrifying spectres and unexplainable horrific events. It was the scariest and most thrilling summer any kid could possibly imagine. Thankfully, no one was ever injured too badly, but Dipper and Mabel had actually saved each other’s lives on more than one occasion. They also survived a challenge to the trust they had for each other, hurting each other more than any monster could, before they successfully repaired their trust before the end of the summer.

They took it all in stride, and by the time autumn came and school began, their already-close sibling relationship was firmly cemented. As the year went by, the twins loyally looked out for each other. They did homework together, helped each other with household chores, and supported each other at school. They even enjoyed just hanging out at home together. Of course, they had other friends, but no one doubted that they were each other’s best friends.

When the next summer came around, they pleaded with their parents to let them go back to Gravity Falls. Their mom and dad had never been given the full story of the adventures they had experienced, but they had read the news accounts. They knew that the kids had been involved in many dangerous occurrences and were reluctant to let them return. And they did not know if they could trust Stan any longer, as his shady involvement with the strange events was revealed. However, it was apparent that the conspiracy that had unravelled last summer was now over. Grunkle Stan explained what had happened and why he did what he did, and reported to the Pines family that everything was normal in the rural town, far more so than he could remember in thirty years.

Also, the legend of what had happened the year previous had spread to the public, and the tourist trade was hotter than ever. Stan basically begged for the twins to be allowed to return to help him at the Mystery Shack. Combined with Dipper’s and Mabel’s enthusiasm for the same thing, their parents relented and allowed them to go back for a second summer.

Things really _were_ different the next summer. As Stan had reported, the weird happenings seemed to have disappeared. Dipper and Mabel hadn’t once needed to run screaming from a zombie, or face down a ghost. There was not a shapeshifter or manotaur to be found. Bill Cipher appeared to be banished for good. Even the little creep Gideon had been locked away in an out-of-state institution after his last escape attempt.

And the tourists had indeed flocked to Gravity Falls. Stan had years ago converted his run-down home in the woods into the “Mystery Shack” and advertised it as the place to see strange and scary artifacts. He had filled it with unabashedly fake items and took advantage of the gullibility of his visitors. After the last summer’s publicity though, many people came to Gravity Falls to see what “really” happened there, so Stan changed his business model. The Shack was now “Ground Zero” of the conspiracy, and Stan profited from his (and his great niece and nephew’s) pivotal roles in the story, at least the parts of the story that they were permitted to (or wanted to) tell.

The people of the town had changed, too. Most of Dipper and Mabel’s friends in town were gone. Mabel’s two best friends from Gravity Falls, Grenda and Candy, had moved away after their families were spooked by the events of the previous summer. Temporary loss of gravity, causing wide-spread property damage, can do that to people. Wendy was still around, and worked at the Shack occasionally, but she was needed in her family’s lumberjack business more and more, and had a lot less time to hang around with the kids. And the NorthWest family was rocked by lawsuits brought against them for the family’s illegal business practices: their daughter Pacifica had shared a spark with Dipper for a short time, but she was sent to a posh boarding school in upper New York State while the family scandal was being litigated.

All this added up to a summer that was very much _not_ what the twins had expected, or wanted. They had worked long hours in the gift shop of the Shack, sometimes seven days a week. Even on their occasional days off, Stan wanted them to be nearby so that they could pose for pictures with the tourists because of their minor celebrity status. They never got to visit the lake or the town pool once. Unlike the last summer, there was no grand adventure, and no other friends to share it with even if anything was to happen. They were tired and bored. At the end of most days, they trudged up to their “bedroom” (the attic of the Shack, where their beds sat on either side of the space, beneath the high sloped walls) and grumbled about what a disappointment this summer was, compared to the year before. They agreed that they probably wouldn’t want to come back again the following year. One thing they thought they’d miss was how they would chat across the room after the lights went out: it was a ritual they had cultivated, their own private time to share secrets and get advice from each other, away from everyone else. They didn’t get to do that during the school year, since of course they had separate bedrooms at home in California.

The only good thing about the summer was that Stan had acknowledged that the twins had been a big part of his financial success, and recognized their hard work. Demonstrating generosity unusual for him, Stan decided not to take advantage of the kids and paid them (somewhat) fair wages for their labor. Since they had little opportunity to spend their money, by the end of the summer they had saved several hundred dollars each.

It had been Mabel’s idea to spend much of this money on a once-in-a-lifetime birthday celebration. Together, they decided that it would be awesome to have a weekend in the city, seeing places they had never seen, doing things they had never done. With an entire day, they could do one thing Dipper wanted to do, then something to Mabel’s liking. They also wanted to be “fancy” for once, to go out for a nice dinner and see a live show, as a conclusion to the birthday extravaganza. None of this could happen in their small town: they wanted to go to Portland, Oregon’s largest city.

However, it was not just a matter of money. Portland was almost a four-hour drive from Gravity Falls. Someone needed to drive them there. Someone needed to have a credit card to reserve tickets. Someone needed to arrange to book hotel rooms. Quite simply, they needed Grunkle Stan to go with them.

And now he was summarily killing their plans. They silently communicated to each other that they had to turn up the guilt factor.

“But we’ve worked really hard for you for over two months,” reasoned Mabel. “School is only a few weeks away, and we’ve not had any fun at all this summer!”

“Imagine how many of the dummies that you’ve had through here that would never have come at all if not for what we did last year,” said Dipper.

“And how many _this_ year went away happy because of our work for you!” added Mabel.

Dipper piled on. “The two of us are probably responsible for _half_ of your added income, all told.” Stan glared at Dipper darkly. “Right Mabel?” Dipper added quickly.

Mabel tagged in. “Yeah!” she said. “At _least_ half!”

Stan was silent and stone-faced. He wasn’t caving, but he wasn’t shutting them down, either. The twins knew they were making progress. Mabel switched tactics to blackmail.

“Maybe we should think about just going home to Piedmont, Dipper!” she huffed in a highly inflated manner. “How quickly do you think we could be on a bus heading south?”

Dipper smiled shrewdly. “Oh, I don’t know, Mabel. Maybe by this time tomorrow. Say, Grunkle Stan, don’t you have two busloads of Japanese conspiracy fans arriving in a couple of days? They usually have tons of cash for spending on mementoes, and stuff like signed selfies with “the Mystery Twins,” don’t they? Are you going to have enough help around the Shack when they get here?”

“All right all right all right!!” exclaimed Stan. “Ugh! What a couple of evil little twerps you are!” Stan paused, hand over his eyes, as he tried to think about the plan the twins had presented minutes before. Dipper and Mabel, for their part, excitedly but silently waited.

After almost a minute, Stan finally said, “For the record, I want you two to know that this little stunt of yours is manipulative, underhanded, and unethical. I see that I’m finally getting through to you, and I’m proud of you!” He cracked a small toothy smile, then more seriously he continued, “But really, you have to understand that going away for a whole weekend would be a lost opportunity to pull in a big wad of cash. I can’t throw that away, it’s just not in me.” Dipper’s face started to fall, and Mabel looked down.

“So instead of your plan, let me tell you _my_ way to get you to Portland for this birthday bash of yours,” finished Stan, smiling broadly.

The kids reacted immediately, making sure their uncle wasn’t joking around. When he assured them he was serious, they let loose celebratory whoops and hollers. Striking an over-exaggerated pose of triumph, Mabel made a fist and raised her right arm to Dipper. Dipper happily duplicated the pose, and then they tapped their fists together to mark their latest success.

Stan had always thought the fistbump was a cute tradition that the kids shared. He envied their wonderfully strong relationship, one that he knew from personal experience was rare in siblings.

* * *


	2. Onwards!

* * *

Mabel and Dipper’s plan was to spend the whole of their birthday doing stuff they wanted to do. They needed the entire Saturday to do this, so they wanted to stay in a hotel on Friday and Saturday nights. They wanted Stan to drive them to and from Portland, arriving sometime on Friday and leaving Sunday morning. What Stan was supposed to be doing with his time all day Saturday was not really fleshed out by the kids.

Stan’s modifications to the twins’ plan was subtle, but significant. He had no problem purchasing theatre tickets on his credit card for the kids, or booking the hotel (provided, of course, the twins paid him back). But you can’t check into a hotel without presenting your credit card, and Stan would have to do this in person.

The Mystery Shack couldn’t run without him: Mabel’s brief attempt to be the boss last summer had proven that. Stan couldn’t give up all that weekend’s business by being away, but he _could_ justify closing up just on Friday afternoon. He would drive with the kids to Portland, check in, hand the door passkeys over to the kids, then drive back home. Dipper and Mabel didn’t need to present a credit card to check out, as his was on file. Then on Sunday, Stan would send Soos to the city to pick them back up again. This part scared Stan a bit, but the man-child had matured quite a bit the last year: he would be fine to drive to Portland and back.

For a brief moment, Stan wondered how safe the twins would be in the city on their own. Then he dismissed it: they had stared down all kinds of supernatural incidents when they were only twelve. He had no doubt they could handle a day in the city as they turned fourteen. They were a great couple of kids, and they had earned a big vacation day for themselves.

* * *

The last weekend of August arrived quickly. To show their gratitude to their uncle, Dipper and Mabel had worked in the Shack extra diligently and without complaint for the two weeks since the birthday trip had been approved. They used their off-hours to firm up the details of what they were going to do on their birthday at Portland.

Dipper decided that for his choice of destination, he and Mabel would go to the Oregon Museum of Science and Industry. He had never been too ashamed of showing his nerdy side, and thought that not only would he really enjoy the facility, but Mabel might actually show some enthusiasm for it too. He knew his sister was never going to be as bookish as he was, but she was very smart and never gave herself enough credit. Enjoying a learning experience would be a great present for her on their birthday. They’d arrive at the start of the day and leave at around lunchtime.

Mabel couldn’t help herself. She wanted to go shopping, and planned for her and Dipper to go to Pioneer Place, a downtown mall, where they would get lunch and an afternoon of browsing the stores. It had been a long time since she had seen the inside of a big mall.  It wasn’t just mindless ogling of stuff: school would be starting just a week after their big day in the city, and they would be getting back to California with only a couple of days to spare (including Labor Day, when most everything would be closed). They would need clothes and school supplies, and she was going to make sure they would be prepared (and maybe get some shiny things, too). She hoped Dipper wouldn’t be bored by the time they were to leave late in the afternoon for their hotel.

They would be bringing “dressy” clothes with them: Dipper had a nice shirt and pants, but would have to buy a jacket and tie at the mall in Portland, while Mabel had a medium-length dress and matching jacket she had brought with her from home down south (she had brought them “just in case I needed them”). They would change at their hotel room, then head a few streets down where they had reservations for dinner at Morton’s, an upscale place that specialized in steak and seafood. Both kids hoped they didn’t make any mess on their clothes, because after that, they would go straight across the street to the Keller Auditorium, and see the production of “Les Miserables”, their first big-time live theatre performance. Mabel was giddy with anticipation of the event, and was very happy that Dipper also seemed to be enthusiastic at the prospect of the dinner and show.

The drive from Gravity Falls to Portland seemed to take forever (for the twins because of anticipation, for Stan because of their incessant babble), but eventually they arrived at the Hilton Portland Hotel. By the hotel’s policy, the room naturally had to include an adult, so Stan had booked a room for three. The room included two queen-sized beds, but of course he wouldn’t actually be staying, so that was perfect for the kids. As Dipper inspected the television and cable box in the high class room, Mabel luxuriated on top of the bed she had chosen, gleefully anticipating having two nights sleep with such a huge amount of bed space.

“You’ve got your debit cards, right?” Stan asked them both. Both nodded, rolling their eyes because this was the third time he had asked the question. “And your cell phone?” Stan added, looking at Dipper.

“Right here, Grunkle Stan,” Dipper deadpanned, patting a pocket in his vest.

“Good. Don’t use it unless you need it, but make sure you’ve got it. I kind of need you to come back, your parents might not like it if I don’t send you home next week,” he added, trying unsuccessfully to add his gruff humor to cover up any small amount of worry.

Stan gave them both (uncomfortable) hugs, wished them a happy birthday, and closed the door while grumbling out loud at the long drive back he faced.

* * *

After they had found homes for their bathroom items and taken some clothes from their bags, Mabel grinned at Dipper. “Wow, we made it! I’m _so_ excited!” she squealed.

“I know, right?” Dipper replied, enjoying Mabel’s enthusiasm. “What do we want to do now?”

“I don’t know! We planned out tomorrow completely, I never thought about tonight!” she said. She thought for a brief moment. Dipper was always asking her for her input, she always loved that about her brother. “Well, whatever we do, we’d better not stay out late, because we have a _lot_ going on tomorrow.”

“Okay, no problemo,” agreed Dipper. “Let’s just go find a McDonald’s and make up our minds while we eat.”

“McDonald’s? Yes!! It’s been too long! _Onwards Aoshima!!_ ” Mabel howled as she dashed down the hall toward the elevators. Dipper chuckled fondly as he closed the door to their room, then chased after his crazy sister.

* * *

Following a sit-down serving of burgers and fries at McDonald’s, it was after 8pm. The twins settled on simply returning to the hotel for a quiet evening and getting to sleep early. Neither one of them wanted to risk being overtired and sleeping past the alarm the next morning, not with the full itinerary they had planned.

Following an entire life of routine, they knew without speaking what the process was for getting ready for bed. Dipper always went to the bathroom first, for the simple reason that he would always go to the toilet, get changed into his undershirt and sleeping shorts, and brush his teeth in the minimum time required. Mabel would then get ready at her own pace of getting into one of her long sleeping gowns and brushing her (now thankfully braces-less) teeth, a process which often included several interruptions for hairbrush-microphone vocal performances to her imagined audience.

Neither had really noticed that their siblings, over the entire summer, had both taken to visiting the bathroom for prolonged periods during the daytime at the Mystery Shack. Both had discovered masturbation in the school year since the previous summer vacation, but while at home they had the privacy of their own rooms, here in Oregon there had been much less opportunity to be alone. Their daytime bathroom sessions allowed them time to take care of themselves with no attention from anyone else. But as much as the twins confided in one another on almost everything, this was a subject that neither even considered sharing, as much out of concern for the embarrassment of their siblings as for themselves. Both thought they were the only one of the two who masturbated, and each was blithely unaware of the other’s sexuality.

Each of them, however, was _keenly_ aware of their own present sexual issue. That issue was that neither Dipper nor Mabel had been presented any opportunity to masturbate that whole day. They had worked at the Shack into the afternoon until Grunkle Stan closed up early, and then they got on the road for Portland immediately. The twins were too distracted to think of getting themselves off at that time, in any rate.

Now, though, both were quietly uncomfortable and on edge, knowing exactly what they wanted to do and unable to figure out how to accomplish it. Both kids wondered the same questions to themselves. Could I be heard through the bathroom door? What if he/she really needs to pee and I get caught? That was too horrifying a thought to even contemplate for either of them, but they didn’t examine exactly why they felt that way.

So neither one did anything about relieving their sexual tension that evening. They watched some cable TV (a novelty), then both agreed that they should get to bed. Despite their practiced bedtime routine, Dipper and Mabel didn’t engage in their usual lights-out banter that night. Both were secretly afraid that they had weirded out the other, because of the way they perceived themselves to be acting. Still, they soon fell sound asleep, comforted by their awareness of each other’s presence in the room.

* * *


	3. The Best Part of Waking Up ...

**Notes for the Chapter:**

> NSFW content to follow in this chapter.

* * *

The alarm sounded, and Dipper woke up quickly. As usual, Mabel took much longer to rouse, so as usual Dipper left the alarm going and started getting up. Mabel groggily tossed her pillows in the direction of the end table, to no avail.

“Come on, Mabes,” called Dipper. “We need to get going. Up and at ‘em!” while he tossed one of Mabel’s pillows back at her head.

“Hey!” complained Mabel’s muffled voice, her head buried face-down on the mattress. She half-raised her head and didn’t appear to process where she was. Not seeming to care regardless, her face fell back to the bed.

“C’mon, Mabel,” Dipper said, more gently this time. He sat down on Mabel’s bed beside her. Not so much as a twitch came from her. He grinned slowly, as he knew what to do to get her up.

Trying to keep a tune as best as his still-cracking adolescent voice allowed, he started in. “Happy Birth-day to uuussss…” he sang quietly, then paused. A smile crept across Mabel’s face.

“Happy Birth-day to uuusssssss…” This time, Mabel managed to match Dipper’s rising volume, pushing herself up with one arm while she struggled to clear the sleep from her eyes and hair out of her face with her other hand.

“Happy BIRTH-day dear MabelandDipperrrrrrrr” (or “DipperandMabelllllllllll”, depending on which of the now-loud voices you were listening to) as Mabel sat up gamely, then pushed herself up to her knees. Dipper rose off the bed and stood, and they moved to the final line.

“ _HAAAAAPPY BIRTH DAY TO UUUUUUUUSSSSSSSS!!!!!!_ ” they bellowed together, Mabel now standing tall on the bed, and Dipper jumping up to join her. Then they fell down to the bed in a fit of childish laughter. They had thought themselves very clever when they created their own birthday song when they turned four years old. Now ten years later, they still loved the tradition of singing it together. For the last several years, the introverted Dipper had always felt self-conscious letting anyone but Mabel hear him sing, so here in the hotel room was the perfect place to be free.

Mabel was delighted to see Dipper be able to let out his silly side, and decided to pounce on him. They hadn’t play-wrestled in a long time, but Mabel still held the advantage of being far less ticklish than Dipper. It had never taken Mabel long to force Dipper into a squirming mass of total defeat, and this turned out to be no exception. After she accepted his surrender, she affectionately punched his arm.

“Thanks, little bro,” Mabel teased, rubbing in how she was born five minutes before Dipper, and thus was his older sister. “I’m up now!”

“So is this whole floor in the hotel, probably,” Dipper added, trying to regain his breath. He was still in a fetal position, looking like he was expecting another tickle attack shortly. “I think we’d better get out of here quick before we get complaints.”

“Ah, stop ackin’ all cray cray!” Mabel replied happily. “It’s our birthday! We’re allowed to be nuts! Actually, I was wrong a second ago. _Keep_ ackin’ all cray cray!” she laughed, as she launched herself off the bed towards the bathroom.

“Hey, I always go first!” called Dipper, lifting his head from the bed.

“Snooze you lose, pal!” Mabel retorted, then quickly closed and locked the bathroom door before Dipper could even get off the bed.

* * *

Dipper had a problem. A “hard” problem. His problem was the degree to which his penis was erect, and that degree was a high number.

Mabel had no idea what that tickling match had done to Dipper. Having a girl, even one’s sister, grab a boy all over his body, then drape her body over him to hold him down while she digs her fingers into his ribs and stomach, is a sure-fire recipe for a hard-on. Dipper hadn’t gotten up after his surrender not because he was tired out: he simply didn’t want Mabel to see his erection.

Mornings were problematic for Dipper, and his attempts to tame his occasionally unruly organ. He would always wake with a partial to full-blown erection, but it also usually calmed down shortly afterwards so he could avoid having anyone, particularly Mabel, see it. But if it didn’t go down, he had found that the one way to make it go down was to force a bladder full of urine through it. This is a somewhat long, actually painful process for the male of the species, and just getting the stream going can require patience and supreme effort, but the end result is certainly going to be a relaxed, soft penis.

Of course, he knew the other way to make it go down, and that was to have an orgasm. But that took time and concentration, and certainly it took some privacy.

Dipper found himself with no way to perform either action. The door to the only toilet available to pee into was now locked with his sister inside, and he couldn’t exactly just start tugging himself when she might come out of the bathroom at any time.

He had no choice but to tough it out until she came out of the bathroom. He sighed and tried to think un-sexy thoughts.

* * *

Inside the bathroom, Mabel had stripped to step into the shower, but paused to appraise herself in the mirror. She had a healthy body, and a healthy body image. She knew she didn’t have to look like a supermodel to be pretty, and she was happy with what she saw.

Mostly happy. _I wish that my body would hurry up and grow some breasts, for pete’s sake!_ Mabel wasn’t flat as a board, but she was far from “endowed”. The one minor advantage of having small breasts is that they don’t really require a bra to support them, and Mabel rarely wore one. Of course, a bra can help hide nipples from peeking through a thin fabric top, and Mabel’s solution to that was easy: she just continued her long-standing tradition of wearing big and baggy sweaters over a tight t-shirt. _What had been a goofy fashion statement as a tween is now a practical solution geared for comfort and modesty. Oh, and still a goofy fashion statement, that's a plus!_

Still, she was glad to not be too hung up on her appearance. _After fourteen years_ , she thought to herself, _I'm doing just fine. Some boy will appreciate me very well, thank you very much!_

_Some boy._

_Wait, what boy?_  she thought to herself. _Who’s going to appreciate me? Well, my boyfriend! Then who’s going to be my boyfriend? Who do I want to be my boyfriend?_ Mabel was genuinely confused, and she had to pause to consider this.

It dawned on Mabel that she had no prospects for her next boyfriend. _And wait a minute, when was the last time there had_ been _a prospect? Why didn't I notice that I haven't had a prospect in ... how the heck long has it been, anyways? I always have prospects!_

She had been boy-crazy for years, long before boys her age would ever consider wanting to be a boyfriend to anyone. A romantic at heart, and impulsive, she vividly remembered being infatuated with endless numbers of boys, and had instantly “fallen in love” over a half-dozen times the last summer alone.  Mabel sure remembered that it had been easy, maybe too easy, for that twelve-year-old to just slobber over a new target of her affections.  She was now fourteen, and she realized that she didn’t do that any longer. When had that stopped? It seemed to her it might have been late last summer, or perhaps the beginning of the school year. She couldn’t picture a single boy at her school in Piedmont that caused her heart to lunge the way seemingly countless boys used to be able to do.

 _But it’s not because I don’t want a boyfriend_ , she thought. _I’m almost desperate to have a boyfriend. I just want the right boyfriend. Yet I apparently have no candidates, where as a pre-teen I targeted them left, right, and center! WTF? This is too weird!_

She wracked her brain, trying to come up with some reason for this change. Her thoughts were interrupted by Dipper’s knock on the bathroom door.

“Mabel? Are you getting ready or not? I need to get in there!” Dipper sounded like he was in a bit of pain. He probably needed to pee.

“I’m just getting in the shower. Can you hold it for a bit?” Mabel replied through the door. Dipper groaned in response. “Thanks, Dip!” Mabel called, as she stepped into the tub and pulled the curtain.

After getting the water to the right temperature, Mabel relaxed under the feel of the flowing water over her body. It felt wonderful, as there was much higher water pressure here than at the Mystery Shack. The soothing force of the water on her back and neck relaxed her, and she unconsciously reached for her nipples and pinched them. She almost jumped, they were so sensitive. Now she remembered how horny she was the previous night, and how she wasn’t able to masturbate to relieve the stress.

Mabel’s left hand remained on her left breast, while she slid her right hand down over her stomach to her vaginal area. She lightly caressed both labia and began to rub her clitoris. She had discovered masturbation on her own late last year, and for a short while she thought there was something wrong with her. And even though she now knew that it was completely normal, she still felt odd about it sometimes. Like how when she fantasized while pleasuring herself, she never pictured an actual boy or man with her. Instead, she pictured only an embodiment of the emotions that were her triggers for her arousal: a person whose reality was not important, only that this was a guy that could make her feel attractive, special and loved. _That's kind of weird_ , she thought, since she knew other girls who masturbated usually pictured themselves with hunky movie stars or pop singers.

This lack of a face to her fantasy reminded Mabel of her lack of any knowledge of a boy, any boy, to possibly be her boyfriend.  Dipper had interrupted her thoughts, and now as she gently rubbed herself, she wanted to get back to that topic.

 _Surely_ , she thought, _there must be some boy at school who would make me drool over him._  She ran down the names in her head of her classmates the previous year, looking for one who sparked her romantic interest. _Aiden? Way creepy. Brock? Pig (and not in an adorable Waddles way). Gary? Too boring. Jeffrey? Yeah.. no. Just no. Jose? Obviously gay. Who else? What about Devon? Isiah? Greg? Sandy? Ezra? Anthony? Dipper?_

_Wait… Dipper?_

Mabel gasped. _Dipper? Why on earth did I come up with Dipper’s name?_ She was obviously not concentrating on her task, because she was trying to think of boys that made her want to make them her boyfriend. _It would make no sense to think of Dipper, he’s my brother!_

As one part of Mabel’s brain finished that thought, another part was making the realization that her hands had just started following new orders. Her left fingers were pinching her hard nipple with greater force. Her right fingers were rubbing her clitoris faster and harder.

Then there was a new realization. Mabel’s masturbation fantasy, the faceless embodiment of her emotion, had suddenly coalesced into a clear picture, and she saw that it was her twin brother Dipper! In her mind’s eye, it was now Dipper’s mouth on her breast, and it was his fingers probing deep inside her. She was rocked with the understanding that Dipper was, in fact, exactly the kind of boy she dreamed of in her sexual fantasies. _He's not just the_ kind _of boy, he ..._ is  _the boy I fantasize about! Why have I never seen this before? Dipper is the one I want to be my boyfriend! Dipper is the one who turns me on so much! Dipper, who's always protected me ... and loved me ... I love him! ... I love_ _him!! I_ LOVE _love him!! ... Oh my God! Oh my God Oh my God OhmyGodOhmyGod…_

Mabel was entirely unprepared as the most massive climax she had ever felt suddenly crashed over her like an avalanche. She almost collapsed in the shower, but managed to lean against the wall as she continued to keep rubbing, caressing, and pinching herself, not wanting the feeling to ever end. Wave after wave of pleasure washed over her, fueled by the knowledge that only one boy could ever make her feel this way, and it was Dipper.

Eventually, though, the moment passed. Mabel found herself sitting on the floor of the tub, pelted by the water from the showerhead. She struggled back to her feet, knowing she had been in the shower a long time, but not knowing how long. As she washed her hair, she remembered Dipper was right in the next room, and had been waiting for her to get out of the bathroom. _Poor Dip!_ She shut off the water and stepped out, calling to Dipper that she would be out just as soon as she could. She’d just have to deal with these new feelings after getting out of the bathroom.

As she reached for a towel, she realized that her memory was missing more information than just how much time had passed. Also missing was any knowledge of sound while she was in the throes of her orgasms. _Oh God_ , she wondered frantically to herself. _How much noise did I make while I was in there? And, I wonder if Dipper heard me?_

* * *

Had Mabel actually asked those questions aloud, Dipper would have been able to answer them. To the second question, yes, Dipper definitely heard Mabel. And as for the first question, the answer would be “quite a lot, actually.”

After Mabel finally started the shower, Dipper had sat back down on his bed. Time was taking care of his “problem”, and he was now only half hard. But now he _did_ really need to pee, and Mabel was taking her sweet time.

Faintly through the bathroom door, Dipper heard Mabel groan.  He thought it sounded like pain. Instinctively, Dipper was on his feet.  He had listened to his instincts before, and they always called him to be ready to act to help his sister. In a few seconds he was at the door, knuckles raised to pound the door and ask Mabel if she was okay.

Before he could strike the door, Mabel made another noise: a sharp, short intake of breath, followed by another moan, louder than before.  Dipper could plainly hear it over the sound of the water in shower. His instinct screamed at him louder, demanding he take action for his sister. But a conclusion about the sound had just been made in his brain, interrupting his gut reaction. His conclusion was that Mabel was not, in fact, in any pain at all.

To understand how Dipper reached this conclusion, one must understand Dipper himself.  He was very much like any other young teenage boy, in some ways. One of those ways was that Dipper, like most boys, was attracted to pornography. Looking at pictures of naked women and reading stories of sex has been a standard part of growing up as a boy for decades. But Dipper hadn’t seen all that much by this point in his life. He didn’t have friends cool enough to have access to printed magazines or books, and Dipper was smart enough to not want to have possession of hard copy anyways.

Dipper knew the better solution: the Internet. It was a perfect porn distribution tool, and he had figured out the purpose of the web browser’s “incognito mode” a long time ago. All he lacked was an abundance of opportunity.  Grunkle Stan had no Internet connection at all at the Shack, and at his home in California his parents had put the family’s PC (the only one the twins were allowed to use) out in the living room. Still, Dipper had gotten good at being able to steal a quick look at some of his favorite material, then quickly destroy the evidence with a fast ALT+F4 when anyone might be about to enter the room.

Only once had he managed to find himself alone in the house for enough time to watch a porno movie. It was only about twenty minutes before he heard his mom’s car in the driveway, but it certainly was enough to prove to him that actual video and audio of explicit sexual foreplay and intercourse was a much stronger stimulant than photos or stories. He had watched it only the one time, but the details were burned permanently into his memory.

One of those details was the sounds the young woman in the movie was making, over the course of most of the twenty minutes Dipper had watched. And the noises he was now hearing from Mabel in the bathroom sounded a _lot_ like that!

Dipper gaped at the door. _Mabel? Was she….. turned on?_ Another gasp and moan escaped through the bathroom door. _Wow_ , thought Dipper. He hadn’t really considered that girls masturbated like boys, or that _Mabel_ could ever be masturbating, like he did. _Was she really getting herself off in there right now?_

Conveniently, Mabel answered his unspoken question. The next sound her brother heard was a very sharp intake of breath and an unmistakably clear, urgent whisper of “Yeeessssssssssssss!!!!!!!”

Dipper was frozen to the spot, unable to stop listening to his sister. His need to empty his bladder was completely forgotten. And his erection was back to full strength.

Obliquely, he realized he wasn’t bothered by the fact it was Mabel that was causing these erotic feelings in him. He supposed she was very pretty, if he was any judge, and of course he liked his sister. Well, he loved his sister, of course, and, well, but…. he wasn’t supposed to feel _horny_ about her. But he quickly guessed it wasn’t hurting anyone for him to just fantasize about her now, especially since she was providing him with a private recital.

If he was thinking about Mabel, Dipper started wondering about what guy Mabel was thinking about in there? _No_ , he pushed that consideration away, as the thought provoked a quick feeling that was decidedly not arousing, so he didn’t want it.   _Whoever he is_ , Dipper thought, _I don’t want to know him_. As he forced it from his mind, he still idly examined the emotion. _It's … anger? Loneliness? No, neither of those, but it's definitely not a pleasurable feeling._

Then it was forgotten, as suddenly, a whole new class of noises erupted from the bathroom. Dipper could hear accelerated gasping, followed by a quick succession of “ohmygod”s, and then almost a keening wail. _Oh man,_ he thought, _is she still alright?_ Mabel repeated the noise again, then gradually transitioned to a long series of heavy gasping, so heavy that it sounded like she was sobbing. It seemed like it was going on forever.

This performance was almost too much for Dipper. His arousal was virtually total, his penis as hard as he could imagine. If he even touched or arranged himself, he didn’t think he could stop his orgasm if his life depended on it. All he could do was slowly ease his way back to the nearest bed, and sit perfectly still until Mabel let him into the bathroom. Mabel’s ecstatic noises continued to emanate through the door. Dipper’s tension was actually painful.

* * *

Mabel hadn’t brought in one of the hotel’s big housecoats into the bathroom with her. She’d have to be satisfied with wrapping herself in a large towel so that Dipper could get in.

Before Mabel opened the door, she knew she didn’t want to look at her brother. She knew that if he heard her, he’d probably have something to say, or at least give her a knowing leer. _Under the best of circumstances, I might be able to handle that (but it would still be really embarrassing)._ But she was also dealing with her new-found knowledge that this same boy who might tease her was also the boy who made her feel so intensely horny, and safe, and …. loved! And that he was her brother.  And that they were about to spend the entire day together. There was no doubt that she would shatter if he teased her right now.

She quickly opened the door and marched straight past Dipper, who was sitting on Mabel’s bed with his head down, elbows on his knees. He glanced up, muttered “thanks,” and immediately entered the bathroom, locking the door behind him.

 _Well, that was okay_ , she thought. _At worst, he knows what happened in there, and is choosing to be polite. And at best, I wasn’t noisy at all, and he really just needs to pee, really really badly. I can deal with that!_

As she pulled on a bathrobe and towelled her hair dry with a second towel, Mabel started examining the situation, and began to despair over how any of this could turn out. _For starters, Dipper would never feel the same way. I know he loves me, and he's proven that over and over, but he couldn’t be_ in _love with me! He thinks of me as his silly sister!_ Was she doomed to living through the remainder of her youth, so close to the source of the most intense feelings of her life, yet forced to stay silent?

Then she considered that Dipper may not even “get” any of how she felt. She knew he’d had crushes on girls before, but she’d never seen him do or say anything remotely sexual.  But she _had_ seen him quickly closing programs down on the computer back at home, just as she would be walking in the room. It might have been a porno web site. Mabel knew a lot about what boys go through when they start to become men, when she (unwillingly) received a full education on the subject from Grunkle Stan. Mabel had hit puberty already: her first menstruation had arrived a few months ago, just before school let out. Boys were supposed to start producing sperm at some point. She wondered if Dipper had yet reached that milestone.

* * *

 _A towel!_ Dipper agonized over the last thing he saw before he entered the bathroom. _She was wearing only a towel!_

After he locked the door, Dipper could hardly contain himself. Carefully, but very quickly, he got out of his shirt and shorts and stepped into the tub, not even managing to turn on the shower. Three strokes, in under two seconds, and he was past the point of no return. He continued pulling furiously on his penis.

His whole body shuddered with the intensity of the climax, every muscle tensed. He involuntarily held his breath as his testicles struggled to push their supply of semen out through his penis, made more difficult because of his full bladder. Still, he managed to keep up the stimulation.

When the first stream finally erupted, spraying the wall of the tub stall, Dipper almost screamed with pleasure mixed with pain. Almost. A tiny part of his brain remained vigilant, demanding that Mabel could _not_ know about this! He knew he could never explain to her why he could be so turned on by her and her sounds of pleasure. She would hate him! No, he had to somehow keep silent.

And he managed it. Somehow, hyperventilating with his mouth wide and making as little noise as possible, he was able to quietly ride out an orgasm that was by far the strongest of his short sexual life.

* * *

Both Dipper and Mabel managed to pull themselves together. They both were hiding feelings that they couldn’t fully explain, and even if they could, they were already running late.

Dipper had taken his shower and sprayed down the walls of the tub stall, now feeling a bit guilty over how he had dirty thoughts about his sister, but only a bit. He was also a bit down because of the fact that some guy out there was awfully lucky, that he (whoever he was) had what it took to make his sister feel so aroused, and found he was actually jealous (Dipper successfully identified the emotion that had eluded him earlier). _Why would I be jealous? That's dumb. But could Mabel have actually been trying to_ make  _me jealous? Surely she knew she could be heard through the door, what with the sheer decibel level she produced. She must have intended me to hear her, but why? Then she paraded around in just a towel._ It was too uncomfortable to process, and he just wanted to pretend it had never happened, at least for now.

Mabel returned to the bathroom to finish getting dressed and to fix her hair, silently pondering her newly identified feelings for Dipper. The feelings of love confused her. She had been taught, of course, that a girl can’t feel _that_ way about a brother. Not _shouldn’t_ feel that way, _can’t_ feel that way! But she most assuredly _did_ feel that way! So what did that mean? Was she a degenerate? No, she was certain that she wasn’t. But she _was_ sure that her feelings were taboo, that no one would be supportive of her feelings. This was going to be difficult to deal with.

Soon they had completed their individual tasks and were ready to leave, and met at the door. They both actually looked at each other for the first time since their impromptu wrestling match.

Mabel was relieved to find herself looking upon “her brother” again. Dipper looked completely normal in his customary t-shirt, vest, and cargo shorts, and of course his trusty pine tree ball cap. She still didn’t know how much he heard of what she experienced in the bathroom, but he was giving no indication he had heard anything at all. She found she could put her feelings for him on hold for now. _I'm ready to just have a great day with my dorky brother!_ The thought of the fun day to come brought a big smile to her face.

That smile was exactly what Dipper needed to see. He knew how genuine it was, and he couldn’t help but smile back. He was so much more relaxed after getting himself off in the shower. Gone for the moment was the sexy girl that seemed to be trying to play on his emotions for some reason, and back was his favorite goofball in the world, complete with “beaker and test tube”-themed baggy sweater. _What a great sister!_

He opened the door to the hallway. “C’mon, lets get going,” he said, nodding to the open door.

“Righto, old chap!” cried Mabel in a terrible British accent as Dipper snapped closed the door to their room. “Get it? Old? ‘Cause it’s your …. birthday? Boop!” Mabel poked her finger into Dipper’s cheek as they strolled down the corridor. “Oh, me too! Boop!” Mabel poked herself in the cheek, then poked the Down button as they arrived at the elevators. “Boop!”

Dipper rolled his eyes and smiled again.

The twins were off to have the best birthday ever!

* * *

 


	4. She Blinded Me With Science!

* * *

The science museum was located on the other side of the Willamette River, about twenty minutes from the hotel for a pedestrian. They had planned to walk, but because they were late leaving, they decided to dig a little further into their savings and take a cab. They arrived in time to be in the first group of people through the gate as it was opened.

Dipper was in heaven. He knew they had only a few hours, so he raced through to absorb as much as he could. Mabel wasn’t quite as interested in the exhibits, but she wanted Dipper to be happy so she tried her best to keep up with his insatiable curiosity for knowledge.

Mid-way through, Mabel got infatuated with a big Rube Goldberg-like machine with rolling and bouncing balls, ramps and levers going all different directions, and lights and gongs going off to mark each event.  She was so enamoured that she didn’t pay attention to Dipper calling her that they needed to move on. Dipper sighed, figuring the contraption would keep Mabel’s attention for days if he didn’t take action, and so he grabbed her hand to drag her away. Mabel was used to casual touch from her brother, but after her realization that morning, the simple act of holding Dipper’s hand sent a little jolt of excitement through her.

After that, Mabel made sure that she “held up” her brother three more times, so that he might need to come take her hand again to keep her going. Each time, she made sure to keep holding his hand a bit longer than necessary, finally adding a squeeze the final time. She couldn’t help but try to signal Dipper that she liked having him holding her hand.

Dipper noticed after the third time he had to pull her along that Mabel was being “touchy feely”, more so than usual, and that she had to be faking these bouts of distraction. What was going on in her head, though, was a mystery. What was she playing at, he wondered?

As Dipper prepared to head across the central gathering space to the Turbine Hall, the only exhibit area they had not been to, he looked back and saw Mabel apparently beguiled by a display detailing the production of renewable energy, of all things. _Seriously? She expects me to believe that this isn’t a game of some kind?_ Knowing it somehow involved him guiding her around, he warily grabbed her hand again and pulled her with him, if for no other reason he wanted to get the joke over with sooner than later. He started weaving through the ever-growing crowd of patrons, Mabel needing to follow behind while still grasping her brother’s hand.

Then Dipper had a sudden sinking feeling that Mabel’s clinginess had to be related to the “shower incident” that morning. Maybe all that noise she made was just an elaborate act he was _supposed_ to overhear. _Oh God!_  he thought. He was now instantly certain that she knew exactly what he did when he went in the bathroom after she got out! _She's preparing to laugh it up at me here in public, where I can't run and hide!_

Right on cue, he felt Mabel squeeze his hand, right in the center of the main hall. With supreme trepidation, Dipper stopped and turned his head to Mabel, expecting to see her watching him with smugness, with some over-exaggerated innuendo thrown in for good measure.

What he saw was a small, shy smile on a face that was tilted down only slightly, and wide eyes looking back at him with sincerity. It was an expression of … affection?

That was, to put it mildly, not at all what Dipper expected. Unprepared to respond with any kind of smoothness, he glanced down to where his and Mabel’s hands were joined, then looked back to Mabel’s face, forced a lame toothy grin and a fake chuckle, squeezed Mabel’s hand back for a split second, and then “dead fished” his hand so that Mabel would _just take the hint and please, pretty please could she just let go of my hand so that this whole painfully awkward scene can just end?_

Mabel let go and instinctively glanced away. She feared she had made a big mistake. She had just freaked out her brother. _And now he's scared. Stupid, stupid! I have to focus on being more like a “normal” sister, because I'm close to ruining our birthday, and maybe more than just that!_

Dipper watched Mabel’s face fall. She tried to cover it, but it was there. He knew he’d hurt her, but he didn’t really know what had just happened.

What better way to handle an uncomfortable situation than to clumsily change the subject? “Let’s head to the last hall,” Dipper blurted, gesturing toward the final exhibit space. Mabel shrugged in agreement.

* * *

Dipper immediately spotted the perfect way to distract them from their mutual discomfort. He pointed toward a large metal machine that looked like an oversized old-fashioned joystick. “That’s a Van de Graff generator,” he told Mabel excitedly. “Come on! You’ll love this!” Mildly curious but thankful for the change in subject, she followed close behind Dipper.

Mabel saw that this was one of those things where you put your hand on the machine and it makes your hair stand on end. “Oooohh, yeah, I always wanted to try one of these out!” she exclaimed, excited despite herself. Her long hair was perfect for this. She took out her head band and hair ties, and shook her thick mane loose. Dipper laughed at the way she got a bunch stuck in her mouth. “Get out your phone and make sure you get a picture,” Mabel said. “Then I’ll take yours while you do it!”

As they waited in the short line, they watched others try the machine, listening to the exhibit operator explain what static electricity was, and how it causes sparks when you walk on carpet and touch a doorknob. When it was Mabel’s turn, the operator addressed her. “Wow, that is an _awesome_ sweater. Just be careful, though, with all that wool you’re wearing, the static charge is going to be extra strong, and you might still get a shock when you step down.”

“That’s no problem, I’m wearing a shirt underneath. Here!” she yelled to Dipper, whipping the sweater off and throwing it to him in one quick motion. “Let’s do this!” she said, almost squealing. _I'm going to look so poofy!_

The machine turned on and Mabel’s hair began to stand up, but it was all very long and quite thick, so the effect was uneven. Another staff member suggested she shake her head a bit to loosen the hairs from one another. Dipper laughed hard as Mabel whipped her head around like a heavy metal singer, but it worked perfectly. “Quick, take the picture!” she called out to Dipper, as her hair splayed out in an outstanding fashion.

Dipper held the phone in front of him and zoomed in to frame the shot better. This was when he noticed something about Mabel’s state other than her hair. Knowing how static electricity worked, he realized that Mabel yanking her sweater off had generated a charge in her t-shirt. This charge was obviously opposite to the charge that had now formed in her body due to the generator. It was obvious because her already-snug shirt was now clinging tightly to even the smallest curve of her torso.

A torso that Mabel, as was normal for her, had not covered with anything other than the shirt.

Dipper’s mouth involuntarily dropped open as he stared dumbly at the phone’s screen in front of him. Mabel’s breasts were pert, handful-sized, and had small but beautifully prominent nipples. The twins hadn’t gone swimming together since the previous summer, and with the way Mabel dressed during the day and for bed, Dipper had never seen even a hint of his sister’s developing figure. He was rocked as he looked at her.  _Mabel’s breasts are …. perfect!_   he thought to himself. In a split second he took in the rest of her, seemingly for the first time. _By God, her body is beautiful!_

“What’s wrong? Is the phone okay?” called out Mabel. She could see Dipper’s confused look and noticed he hadn’t indicated that he had taken a picture yet. She had been standing motionless, hand still pressed to the generator, for several seconds now.

That snapped Dipper out of his paralysis. “No, it’s okay!” he called back, trying to zoom in closer to frame her in a “head and shoulders” shot, but the phone’s camera would not zoom close enough. He only ended up taking a picture that showed off Mabel’s chest even more than before.

“Got it? Good! Your turn!” Mabel chirped, waiting for permission to remove her hand to be given by the (now smirking all creepy-like) operator. She snatched the phone from Dipper and pushed him towards the dias.

Dipper shuffled up to the generator, taking off his cap and holding it in his hand in a strange awkward stance. The operator asked him to drop the cap by his feet. Mabel thought, _He looks scared of being electrocuted, of all the silly things. He actually looks kind of flushed_. His hair was thick and wavy like hers, she noted. _He looks like an adorable Pomeranian puppy, what with his hair all big and fuzzy,_ Mabel thought as he was getting the static electricity treatment. And it was fun seeing the birthmark on his forehead again: Dipper was very adept at keeping it hidden from view at all times. She had to coax him to look to the camera, then she quickly snapped several shots. Dipper disengaged himself, retrieved his cap, then tried to snatch the phone back from Mabel as soon as he reached her.

“Hey, what’s wrong?” she asked, concerned that Dipper just got all weird on her again. She held the phone away, backing up as Dipper tried to get it from her again.

“Nothing, I just want to make sure you don’t drop it, or something!” Dipper mumbled back, advancing forward while Mabel retreated.

“Well, wait a second, I want to see how the pictures turned out!” she responded in a huff. Turning her back and holding the phone tight to her body so Dipper couldn’t touch it, she looked down in the direction of the phone, preparing to bring up the camera roll. That was when she finally noticed for herself the effect that the static electricity had made on her t-shirt. It continued to hug tight to her skin, and as she looked down on herself it was painfully obvious that she was not wearing a bra over her embarrassingly small breasts.

Subtlety was not a strong point for Mabel. “AAHHHH!!” she cried loudly, drawing the gaze of everyone nearby as she swiftly reached for her sweater and pulled it back on, still clutching the phone. “Where’s that picture you took?” she said frantically, stabbing at the phone’s screen.  “I’ve got to delete that!”

“No no no!” interjected Dipper, again reaching to stop Mabel from using the phone. “You can’t! I only took one shot. You know … with the hair and everything?”

“But could you see all … this?” she whispered urgently as she waved helplessly at her chest.

“I don’t know … ”Dipper replied, pausing for an extra beat or two. “Maybe?” he added meekly.

Mabel was mortified. “Dipper!” she rasped.

“Alright, alright, let’s just go find a bench and sit and we’ll see if I can fix it. Okay?” Dipper said nervously.

Mabel reluctantly agreed and they found a seat on a wall, then grudgingly handed over the phone to Dipper. He brought up the photos in the phone’s memory, quickly sweeping past the shots of himself with the generator and stopping at the picture of Mabel. It was a good shot, and Mabel’s hair was captured spectacularly. _Mabel’s breasts are even more spectacular,_ Dipper thought, an opinion he noted that she obviously did not share.

“Ack!” she blurted. “Dipper, _please_ delete that picture! That looks terrible!”

“No it doesn’t!” Dipper replied quickly. Mabel gaped at Dipper. “I mean … I can crop the picture later! The shot of the _hair_ is great! I can make it so that it only shows you from the shoulders up, if you need me to.”

“Yes, I need you to!” snapped back Mabel. Then, a bit quieter, she said, “Fine. Don’t delete it. But please fix it, okay?”

“Okay, okay. I can do that, it’s no problem,” Dipper said, words spilling out. “Head and shoulders only. And the hair. It really is a good photo. The detail shows up great. I really like them a lot. _It!!_ ” he corrected quickly, eyes wide. “I like _it!_ The _photo_! I like the photo a lot! And … _them_ , your … your … _hairs_! Yes, your hairs! I like _them_ a lot, too!”

Mabel regarded Dipper carefully. “My ‘hairs’? You like my ‘hairs’?”

“Yes, your hairs!” Dipper repeated with attempted bravado. “Yes, I do!” Mabel heard the crack in his voice as he replied.

Mabel let Dipper off after that, and his attention went back to the phone. His Freudian slip had not been missed. _Dipper likes my breasts! No, he said he likes them a lot!_ Just a few hours ago she wondered if she was isolated or sick, perhaps the only one who was demented enough to feel attraction or love for a sibling. Now she knew that if nothing else, Dipper liked her body, specifically her boobs! She felt a knot of excitement low in her abdomen at the thought.

She glanced over at Dipper again, and saw that he was deleting the pictures of himself that she took of him!

“Hey, what are you _doing_?” Mabel cried.

“Nothing!” Dipper cried back.

“It’s not nothing! You’re getting rid of the pictures I took of you! Why are you doing that?” she demanded loudly.

Dipper panicked.  He could think of no answer, not even a plausible lie, that he could give Mabel for why he needed to delete those pictures. The only answer that would come to his mind was the truth, and he _couldn’t_ tell her that! For all his cleverness, for all the knowledge he had in his brain, he was utterly unable to determine a way out of being caught. With a few more years’ maturity, he might have been able to man up to Mabel, and take her challenge stoically. But at fourteen, his emotional tools were not up to par. Dipper lost control, and in horror realized he was starting to cry.

Mabel’s anger instantly turned to concern. “What’s wrong, Dipper?” she asked him sincerely, putting her hand on his shoulder. At the touch of her hand, Dipper only started sobbing harder.

She was so confused, what had happened so quickly? She looked down to Dipper’s lap and the phone he held, still showing the last of the photos in the camera roll of Dipper that Mabel had taken.  Besides his hair standing on end, Dipper in the photo looked so stressed out about something. Then she noticed it: the front of Dipper’s shorts was tented out, almost comically so. Without thinking, she moved her glance from the phone to Dipper’s crotch. There it was, visible even though he was seated, even though he was now crying even harder. Dipper had a very prominent erection. And Mabel correctly guessed that her breasts were the cause of it.

In a strange way, it made Mabel feel _good_! To know that Dipper could at least see her as attractive, even erotic, meant that her own feelings for Dipper weren’t so abnormal.

Mabel wanted to say something, because Dipper needed to know that she understood. _Really, I_ do  _understand!_ But she set aside that for the time being. First, she had to help him pull himself together: he was crying because he didn’t want to tell her what she had now already seen for herself. _Once that bridge is crossed, as awkward as that will be, I'll be able to try to tell him at least some of my_ own _feelings,_ she mused. _And that will make things better. Right? I just have to lighten the mood at bit, that’s all._

“Dipper, it’s okay. Look … you don’t have to say anything. I think I know what’s wrong,” Mabel said gently. “I can see the … “size” of the problem,” she added with a bit of a smile.

Dipper didn’t see the humor. He pushed his legs tightly together and turned half away. His face turned a deeper shade of red, and he groaned pitifully. But his breathing started to even out.

“And, you know … things like this happen, am I right?” Mabel continued helpfully. “I mean … we’re growing up, and … you know … _hormones_ and stuff?” Mabel was getting more animated. “Things getting all … _sweatier_ … even then before?” Dipper was enduring her “pep talk” as best as he could.

“And besides, it’s not like you’re not like every other boy out there! C’mon, I’ll bet it happens all the time, doesn’t it?” Mabel’s growing enthusiasm to helping Dipper was making her forget the concept of “tact”. She wasn’t any better at tact then subtlety. “You’re probably just laying around, or sitting in class, minding your own business, and then “Hello!!” right!?” adding in a twist of her hips for effect.

“Oh, God!” exploded Dipper, leaping to his feet and pressing the heels of his hands to his forehead. “Just stop! I do _not_ want to have this conversation with you, Mabel!” He looked around and he saw a lot of people watching him. Taking a deep breath, he sat back down. His face was red and wet, but he could control himself. He continued quietly. “Okay, so now you know … I just …” He couldn’t explain himself, so instead he went into apology mode. “Mabel I’m sorry! I’m so sorry! That should _not_ have happened to me. It won’t happen again, I swear!” Mabel tried to interject, but Dipper cut her off. “No, please, just _please_! I just want to forget this happened! Can’t we just forget it and just go on with our birthday?”

“But Dipper …” Mabel urgently wanted to tell him that she didn’t think this was as nearly as horrible as he thought it was.

“ _Please?!_ ” pleaded Dipper desperately, thinking this couldn’t get more horrible for Mabel, wanting to protect her from his depravity. “For me? Please, just _please_ drop this, at least for now! Okay?”

Wordlessly, Mabel nodded her head. While temporary relief poured over Dipper, Mabel felt her heart squeeze painfully in her chest.

* * *


	5. Benefits to Being a Shopping Buddy

* * *

The twins left the museum shortly after, and took the MAX streetcar train back towards downtown Portland. After a quick transfer, they were crossing the bridge back across the river, heading toward an afternoon of shopping at the mall.

Dipper was grateful that Mabel had respected his desire to not discuss the “incident.” He nudged her leg with his knee. “Hey,” he said with a small smile, “I _am_ sorry for freaking out back there. I guess … that was as uncomfortable for you as it was for me.”

“Yeah,” Mabel replied, thankful Dipper had broken the ice. “It _was_ pretty intense.”

“But I’m done with that,” Dipper continued, smiling bravely. “This is _our_ day together, and I want to have a good time, and not be a stick in the mud.” Dipper looked at Mabel’s face for agreement. “Are … we okay?”

Mabel paused for several moments, seemingly for dramatic effect. Finally, she answered his question. “That depends,” Mabel replied craftily. “How good of a shopping buddy are you going to be for me?”

Dipper sighed, but knew he owed her one. “I will do anything a “shopping buddy” needs to do,” he promised.

* * *

Being a shopping buddy sucked.

For Dipper, the first part of the visit to the mall was fine. He and Mabel sat at the food court and ate lunch, reminiscing on the previous summer’s adventures. They stopped by the Apple store and browsed in the Game Stop for a while.

But they found that this was a fairly upmarket mall, with stores that tended toward the high end. As much as Mabel liked to admire the “shiny” things in life, she knew she couldn’t afford most of the clothes and jewelry they were seeing, and they really didn’t suit her well anyways.

So Mabel dragged Dipper around downtown. She found smaller, funkier stores, where she could find stuff that were more to her offbeat tastes, and her more modest means. Not ignoring her brother, she made sure that he found a nice sport jacket and tie, which she knew would go perfectly with his shirt and pants back in the hotel room. But the majority of Dipper’s time was spent waiting on Mabel to look around in a store, try a thing or two on, be forced to offer his opinion on how it looked (and then have the opinion ignored), then on to the next store. The only thing that kept him from losing it on Mabel was his promise to her that he had made on the streetcar.

It was getting late in the afternoon, and they were headed back to the hotel, when Mabel saw one more store she had to visit. It was advertising an end-of-summer sale, and she told Dipper that since fall weather in the Bay area could be as warm as summer in Oregon, she couldn’t resist. Dipper grudgingly followed, under the weight of Mabel’s bags.

While Dipper was looking for a place to unload the bags on the floor and rest his arms, Mabel looked at the “summery” clothes. The shirts and blouses all had such low necklines, and the shorts and skirts looked like they showed a lot more leg than she was used to. She found some of the more suitable pieces she could, and told Dipper to camp out near the change room.

Mabel strutted around in front of the large mirror with some of the outfits she had chosen. The girl who looked back at her from the reflection appeared far more mature and urban, and even Dipper offered that she looked good. Mabel grinned, and found a pair of high-heels to compliment the clothes. She was a bit unsteady on the stilettos, but when she got the strut down, the shoes certainly added to the look. Heading back into the dressing room, she told Dipper she was almost done.

Yawning broadly, Dipper was examining his phone. It was getting late, they’d have to hurry along if they were going to have time to change at the hotel and get to the restaurant in time for their reservation. He heard the dressing room door open, and was putting the phone in his pocket as he looked up.

He was sure that it was not possible for his heart to stop, but it certainly felt that way.

Mabel was still wearing the high heels. She just wasn’t wearing much of anything else. She had put on a criminally small black bikini, which stood out in stark contrast to her fair skin. The fabric triangles were barely large enough to cover much of even Mabel’s small endowments. The strings that connected them were tiny, with knots that invited untying. The strings that held the bottoms were tantalizingly low on her maturing hips. The high heel shoes forced her into a pose that thrust out her breasts more impressively than she had thought possible.

She had a strange mixture of determined mirth and terror on her face as she took two steps out of the change room. She turned, showing Dipper how her long brown hair hung impressively down her nearly naked back. Below that was, well, virtually nothing. The back of the bikini’s thong bottoms were merely strings, which served to draw attention to Mabel’s firm butt. Nothing was left to the imagination.

Looking back at her immobile brother, Mabel chirped, “Okay, I think I’m done now!” Then she strode back into the change room. Or tried to, as she stumbled over her high-heels on her first step and crashed into the small room. “I’m okay!” she cried out helpfully, and clumsily slammed the door.

Dipper’s heart eventually restarted, though his mouth was still agape. _Holy shit!_ That was the only words he could think. The rest of his mind was trying to fathom the wondrous images relayed by his eyes. It was true that he had never in the flesh laid eyes on any girl so close to completely nude in his life. But it wasn’t just her face, skin, and her figure: it was more. It was the attitude, the seductive poses. It was the tiniest mystery of what was still hidden under the bikini. He was hard pressed to imagine anyone could have looked more desirable to him. She was stunning, his very definition of sexy! Everything about her had screamed out to him to ravage her, to forget any pretense of discomfort, any issue of embarrassment or moral questioning.

But he couldn’t forget. Oh, he was very pleased with the display, and amazed that his sister had done this in front of him. But Dipper was at least aware of just what part of his body was sending signals to his brain. These were feelings of lust, and he knew it. That was fine for dirty pictures or porno movies. Someday, when he was older, he wondered if he may be okay with lust for a casual girlfriend. What was the term, a “fuck buddy”? Maybe someday. But this? No, he knew that would be very wrong to act on. Not at his age, certainly not with Mabel! He was simply incapable of debasing himself like that. Dipper’s moral compass easily overcame any urges that his hormones could possibly put forward. He would not be a slave to his penis.

Besides, it was a moot point anyway. Mabel would certainly not be interested in letting him touch her that way! And he cared about her far too much to do that to her!

So Dipper was left with wondering what was up with Mabel, and why she had put on this exhibition. He was thankful that the show had been brief, and that he’d had time to settle down a bit, such that he was now only half-hard. She emerged from the dressing room, carrying several of the clothes she had tried on, plus one pair of high heel shoes and two tiny black garments.  Smiling sincerely at Dipper, she breezed by him and headed for the cashier at the front of the store.

“Wait, what was that all about, Mabel?” Dipper asked quietly as he walked after her.

Mabel stopped and turned. With a playful expression and genuine smile, she replied in an exaggerated tone, “Oh Dipper! I don’t want to have this conversation! Please, _please_ can we drop this, at least for now?” She was mocking his words from earlier, but in a way so he knew there was no actual animosity. Mabel was in one of her silly moods, and she was telling Dipper he would just have to wait for an explanation.

“Don’t forget to bring all our shopping bags!” she said brightly, resuming her route to the cashier.

* * *

The short walk back to the hotel yielded no explanations to Dipper for Mabel’s sudden odd modelling choice. In their room, Mabel sweetly told Dipper that she would tell him everything soon, and that he should be in no hurry. They changed into their semi-formal attire, and Mabel pronounced them a very smart looking couple, indeed!

On their walk to the steakhouse, Mabel cheekily took Dipper’s hand, making no pretense of subtlety like she had that morning at the museum. As they walked, Mabel was prancing and swinging their joined hands higher and higher, all the while commenting on the beautiful weather between humming upbeat pop music. She was hamming up her performance tremendously, and Dipper had found himself more and more amused by her antics, in spite of his curiosity.

Mabel was very pleased with herself. Her off-the-cuff plan was working out perfectly.

The plan had taken just a few seconds to hatch, back on the streetcar from the museum. Dipper had just been apologizing for flipping out over his woody, saying he just wanted to have a good day and move on. Mabel still wanted to tell him that she _liked_ it that he had been aroused by her, but knew that the subject was delicate for him, and bringing it up again now would make him really uncomfortable, maybe even angry with her. There had to be another way to show him.

Then the idea materialized. _I'll show him by_ showing _him! Dipper's obviously turned on by my body, so I'll make sure he gets a real eyeful! Then he'll have to know that I'm okay with being ..._ sensual _... towards him, and that his erection has not only been forgiven, but welcomed!_ Then they’d be able to have a meaningful conversation, where she would try to bring up how she felt about him, that she loved him as much more than her brother. She _knew_ that now, even more convinced of it than she was that morning in the shower. _I just want to touch him, hold him, love him: to be in a real relationship with him. Forever and ever!_

But back to her plan. How could she arrange to have Dipper see a lot “more” of her than he was used to? And wouldn’t he call her on it when it happened? To be sure, she _wanted_ to have that conversation, but it had to be done carefully. _Maybe somewhere a bit public, so I can be sure he won't freak out and he’ll have to listen to me._ She remembered their dinner reservation before the show coming up that evening. The _perfect_ place for their heart-to-heart! So Mabel’s grand reveal had to be just before that. _The hotel room, just before leaving for the restaurant? Just get naked in the bathroom and walk out? No, that would be too much, Dipper would probably have a fit._ Again, she needed a more public setting. How would she manage that? _Well, duh, we're on our way to go shopping right at this moment, how about a skimpy bathing suit? Perfect!_ She informed her brother that he would be her “shopping buddy” for the day, to make sure he stayed close as she found the right moment.

Mabel got lucky, as she was not finding many bathing suits in the stores (given it was late in the summer) when she spotted the store with the end-of-summer sale. Her attention focused on the black bikini almost instantly, but she also saw the other clothes that she actually wanted to try on, so she couldn’t waste the opportunity. Besides, Dipper might see her pick up the swimsuit, and she wanted it to be as unexpected as possible. The high heels were a last-second addition to her plan. She waited until Dipper was engrossed with his phone before plucking the bikini (two different sizes, just in case) off the rack on her way back to the dressing room for the big change.

There was nervousness as Mabel put on the bikini. _Oh my God,_ she thought, _it's even smaller than I thought!_ There was very little coverage of even her breasts. The bottoms only stayed up with the assistance of magic, apparently: how else to explain that they just didn’t fall down over her hips? _And the back! The bottoms don't cover my butt at all, it's just a string down my crack. How do they get away with making things like this?_ But she steeled her nerves, hoping beyond hope that this would work, and forced herself to open the door. Dipper’s reaction was priceless to behold, and it helped her to step out and show herself off to him. His wide-eyed and open-mouthed expression of shock told her that she effect was perfect, and her apprehension disappeared. She turned and struck a pose she hoped showed off her behind. Seeing where his eyes were focused on, she knew that she had succeeded. Mabel was delighted, and even losing her balance on her high heels didn’t dampen her spirits.

Mabel was pumped. Dipper held his tongue on why she did it, as she asked him to. As they approached the door to the restaurant, she was still sashaying around with anticipation. _I'll get him to admit his desire, and then I'll spill my soul to him. This plan is working out exactly as I wanted. How often does that happen?_ she wondered.

* * *


	6. Dinner, a Show, and a Nice Evening Stroll

* * *

The twins were seated at a table in the fancy steakhouse. They had drawn a few stares, as it must have looked odd for two well-dressed young teenagers to have dinner alone in an expensive restaurant.

They were given menus and had their water glasses filled. Dipper gulped as he glanced at the menu, not prepared for just how pricy a good steak dinner could cost. But this was still their special day, and he resolved to not worry about it. He ordered a small porterhouse, while Mabel ordered a halibut and shrimp dinner.

After the waiter left, Dipper leaned forward. “Okay, _now_ are you going to tell me what’s up with you?”

Mabel smiled shyly. “I just wanted to see what your reaction would be,” she replied softly, her goofiness melting away.

Dipper blushed, thankful for the dark room. “I thought that was already obvious from the museum this morning. What were you expecting?”

“Exactly what I got, I suppose,” she said. “And I’m glad you’re talking about this morning. You don’t have to feel bad about it.”

“Thanks,” Dipper replied, looking sheepish. “You do look really good, though. I mean, _really_ good. I mean it, Mabel. That was … _really_ hot!” Mabel beamed at the praise.

“So, you don’t have to worry about how you look, everyone will think you’re beautiful. You’ve got _no_ worries about that!” Dipper continued.

Mabel stopped as she was about to take a sip of water. “What?”

“I’m just being honest here. If _I_ reacted that way to seeing you, you _know_ other guys will even more. I guess … it’s just surprising to me that you’ve got this … body issue. You’ve always been so comfortable with yourself. But hey, like I said, I don’t think you’ve got a thing to worry about!” Dipper finished warmly.

Mabel blinked. She was now realizing that Dipper had to be the thickest, most oblivious guy she had ever known. She had just showed off herself to him in the smallest garment in the known world. She had done it for _him_. But he thought that she was just _practicing_ for someone else? She supposed it was a brotherly-nice thing to say. But she also felt like walking into the kitchen of the restaurant and finding a big frying pan, because Dipper needed to be hit over the head as soon as possible.

Instead, Mabel elected to just keep the conversation going, in hopes of steering him back to her way of thinking.

“Thanks,” she told him. “Have you ever … seen a bikini like that before?”

Dipper reddened again. “No, that was the smallest one I’ve ever seen. I haven’t seen _anything_ like that! Not even …” He stopped, and deliberately picked up his water glass for a drink.

It was too much fun to turn the screws on her brother. “Not even _what_ , little brother?” Mabel teased. “Where _else_ have you been looking?”

“Oh God, Mabel, why are you doing this to me?” Dipper groaned, covering his face.

“Because it’s fun, of course, silly! Now c’mon! Where else?” Mabel shot back.

Dipper paused, hoping his sister would just evaporate. It didn’t happen. “You know, magazines, catalogs … the Internet …”

“Hah! I _knew_ it! You look at porn on the Internet!” Mabel laughed, not disgustedly. Dipper frantically signalled her to lower her voice. Mabel complied. “You are such a perv!” she whispered loudly.

Dipper’s discomfort was palpable.  He looked down at the table, unable to deny it.

“Oh, get over it!” Mabel continued. “I know all you guys do it. Although I don’t know why you don’t just get a _real_ girl.” Mabel was trying to prod Dipper to the closest willing target.

“Oh, yeah, right!” Dipper said bitterly. “Like that’ll ever happen.”

“All you’ve got to do is look around and someone will be there!” Mabel was almost singing, and felt like she needed to wave flags.

Dipper would not take any hints. “Mabel, you don’t understand. There’s a difference! There’s a difference between …” Dipper closed his eyes, “ ‘getting off’ … and having a girlfriend. They’re not the same thing!”

“Well, yeah, one requires another human being, and the other doesn’t!”

Dipper forged on. “No, it’s really … I don’t know how to describe it, but …” Dipper was determined that since Mabel was going to go down this path with their conversation, she was at least going to understand him.

“Look,” Dipper began, trying to be clinical, “I can get all worked up. I get … horny.” Mabel stifled a snicker. “A lot of that isn’t really under my control. I think with my head, but a lot of that stuff comes from …” He stopped, tilting his head and rolling his eyes downward.

“From your _little_ head?” Mabel suggested helpfully.

Dipper winced in pain, then sagged. “That’s actually not such a bad name, I guess,” he said, then continued. “When a guy gets horny, he needs to get off. He can use his hand, or he … uses a girl instead.”

“ _Uses_ a girl?” Mabel piped up irritated.

“Yes! You’re right, yes!” Dipper agreed. “I know. I’ve listened to Robbie talking with his buddies. For the ones who have had sex, it sounds like they just … they don’t really care about the girls they’re with, it’s all about just getting off.” Dipper paused. “That’s not what I want in a girlfriend, though.” The salads for their dinner arrived, and Dipper wanted to wait for the server to leave before continuing.

Mabel waited for Dipper to pick up the conversation, then prodded him on. “So? What do _you_ want in a girlfriend?”

“I don’t know! I’d … need to _like_ her! She would have to be interesting, and fun, and smart, and … stuff,” he finished lamely.

Mabel saw it at once. “Dipper, you romantic scallywag!” she cried. “You want to be in _love!_ ”

Dipper tried to process that statement. “I … guess you’re right! I can’t put words any better than that into describing what I would want.”

“Well you’ve been in love before! You were totally in love with Wendy last summer!”

“I don’t really know that I was,” Dipper remembered. “I think it was more of a crush. I mean, it was really awkward when that whole bunker thing happened, but she’s way older than me, it was just weird. I think if I’d really been in love, I’d have been a lot more broke up about it afterward.”

“Alright, then,” said Mabel, “what about Pacifica? By the end of the summer you were pretty friendly with her. Did you love her?”

“No, it was more like really close friends with her.” He paused, thinking of the change that had occurred, from little rich bitch to a really nice, but damaged, girl. “When I found out all the horrible abuse her parents had done to her growing up, I was happy just to be a normal person in her life.  She had you as a ‘girl’ friend, and she had me as a ‘guy’ friend. I was never her ‘boyfriend’.”

Mabel looked at Dipper. “I thought you two had kissed and everything.”

“We did, and she was the first girl I kissed.  And it was nice and all, but … I knew we weren’t really meant to be more than that. No, I was never in love with Pacifica.”

“And nobody in school?” Mabel wondered.

Dipper almost snorted. “No, no one back home, either.”

Mabel was secretly pleased. _She_ could be Dipper’s first love! She had to be cool about what to say next, though.

“So, then? What’s been missing?” she asked. “What’s some girl going to have to do to make you fall in love with her?”

Once again, Dipper was silent in thought. Then he said, “Nothing!”

Mabel didn’t like that answer. “Nothing?” she repeated, almost distressed.

Dipper smiled at Mabel’s concern for his love life, and tried to explain further. “There’s nothing a girl can do to _make_ me fall in love. That’s up to me! If _I_ like a girl, if _I_ want to be with her, if I … if _I_ think I can’t bear to live without her.” Full realization of his thought finally occurred to him in words. “If I would sacrifice everything … and do _anything_ for her … _that’s_ love!” Dipper stopped and thought about some more. “Yeah! I think that’s how I’ll know I’m in love. Thanks, Mabel!”

“Anytime,” Mabel replied. She was keeping a steady face, but her insides were churning. She was devastated. Dipper didn’t want her, not _that_ way, and apparently there was nothing she could do to force him to change that. Maybe if he was like other boys, she could have used her body to manipulate him, to _make_ him see her as she saw him, as she had been planning all afternoon. But now she understood, something she should have already known: he was _not_ like other boys. He was Dipper, and it was what made him different that had made her love him so much.

The entrees arrived shortly afterwards. For the second time that day, Mabel forced herself to go on as if things were just fine. It was much harder to do the second time.  Their dream day together was beginning to feel like a dream that had been lost.

* * *

Mabel was actually grateful for the performance of “Les Miserables”. It is known as a tear jerker, and with the way Mabel was feeling, she let the water works go. She had never cried so much in her life. Dipper’s eyes weren’t dry either, and both of them felt that they were through the wringer by the time the performance was over.

It was almost 11pm when they walked out to the street with the rest of the crowd. Though it had been a very long day for the kids, Dipper figured that they would be expected to go somewhere after the show. It _was_ a very warm, pleasant night in downtown Portland, so they made the short walk down to Waterfront Park on the river. There were bike trails and lots of grass, and there was a rock and sand beach beside the marina. Because it was the weekend, there were plenty of people around soaking in the nighttime ambiance.

Dipper and Mabel were quiet, enjoying the beautiful night, but mostly just thinking of the day’s events. They engaged in small talk while they strolled in the direction of the marina. Dipper was feeling worn out but content, while Mabel was just worn out. She had filled so many buckets with tears, for the show’s characters and for herself, she didn’t know if there was anything left. Silently, she wished they would just go back to the hotel so she could go to sleep. She knew her sunny personality would come back with a new day. But for now, if Dipper was still wanting to keep going, so would she. She would tough it out for him.

For his part, Dipper noticed that Mabel looked tired, and thought he’d just get one more memory out of the evening before returning to the hotel. Near the water’s edge on the beach area, he had noticed a family of swans swimming serenely through the dark shallows. He suggested that they get a photo, and Mabel gamely agreed. Dipper said that with the low light, they would have to get a lot closer if they wanted the picture to come out, so they carefully walked down to the water’s edge.

They approached the line between where the sand changed from dry to wet. In the low light, Mabel didn’t see a depression in the sand, made when a rock had been pulled out of the sand by a small child earlier in the evening. Her foot went into the hole, causing her to lose her balance toward the water.

If she had just dropped, her legs, bum, and hands would have been sandy, perhaps a bit wet. But instead, she attempted to correct her balance, desperately trying to stay on her feet. Dipper reached for her arm to stop her, but she was out of his reach. The downward slope of the beach and the direction of her momentum resulted in her stumbling directly toward the river at increasing speed. Finally, after two fast lurches into the water, she landed with a large splash and loud shriek in water that was about knee high.

The commotion was heard and seen by several people. Some couldn’t help but laugh, and a few started down to see if they could help.

Dipper saw Mabel was unhurt, shook his head, and laughed softly at his crazy sister.  He gingerly stepped into the water, prepared to help haul her up. He reached her and extended his hand as he asked “You okay, Mabel?” with a chuckle.

Mabel looked up and him. Then she looked away. He had never seen that … blank … expression on her face before.

It was the straw that broke the camel’s back for Mabel’s emotions as she sat in the water. All the anticipation, passion, joy, anxiety, thrills, heartache, and sorrow of the day finally froze in an instant with the humiliation of falling into a river while people watched and laughed. Even Dipper was laughing! Her heart seemingly gave up trying to feel anything, so she decided to just kind of shut down.

Dipper was immediately concerned at Mabel’s change of behavior. He reached down and grasped her hand and forearm, but Mabel pulled her hand free and crossed her arms in front of her chest, partly beneath the water’s surface. She made no move to get up.

“Mabel, what’s wrong?” Dipper asked her, growing more worried by the second.

“It’s too much. I can’t do it anymore,” she said quietly, looking down into the black water’s surface.

“Can’t do _what_ anymore?” replied Dipper. He got no reply. “Come on, Mabel. You can’t just stay here. We have to go back to get you dried off. Let’s get up, let’s go,” he urged. Mabel just kept sitting in the water.

Some passersby had arrived at the water’s edge, one asking if the girl needed help. Dipper replied no, he just needed a minute, and they’d be all right. He turned back to Mabel.

She looked … broken.

Frantically Dipper tried to think of what happened, and what caused this. None of it made sense to him. So many things had gone on that day: the showers they had taken, the static electricity t-shirt, the boner, the bikini, the talk of relationships at dinner, the tears at the show … Mabel falling into a river was practically a mundane event compared to those!

Regardless, his job was to fix this. He had to. And … he had no idea what to do! What do you do for someone who is not physically injured, but just wants to sit in cold river water while fully dressed?

Dipper couldn’t process how this girl was the same girl that he knew so well, who had always seen the positive side of every situation. What had happened? _What could I have done? Did I hurt her somehow? I must have done something wrong. I couldn’t stand it if I’ve hurt her this badly! Surely she knows this? She can’t stay mad at me! I have to be able to do something for her! I’d do anything for her! I just have to …_

His thoughts stopped.

He would do … _anything_ … for her!

He remembered the significance of those words, his own words, from dinner earlier that evening.

And just like that, a wall in Dipper’s mind was demolished. It was a wall that he had built over a long time, meant to protect himself from emotions that he subconsciously knew might overwhelm him. A wall built of practicality, so he would not have to face up to a simple truth:

He was hopelessly, madly in love with Mabel, and had been for a long time!

Instantly, in front of Mabel and several strangers, Dipper faced what Mabel had secretly tried to deal with all day. He quickly had to wage an internal battle between his love for his sister, versus the reasons he knew that such a relationship would never work. Tears unwittingly ran down his face, and his chest was shaking. He unsuccessfully choked down a sob.

Mabel glanced up at the sound. Dipper was crying. Again. He had cried often that day, and if she were in her normal state she would have been more touched that Dipper was wearing his heart on his sleeve.  Still, she wondered what had caused him to lose his control again.

Dipper saw Mabel momentarily looking at him, and inside he leaped for just the smallest improvement in her mood. But what more could he do? Obviously, he couldn’t tell her what he was feeling! But he had to get her up and out of the water. There must be some way to reach her. Convincing her with words didn’t seem to be working.

 _What about the old expression: actions speak louder than words?_ And then Dipper knew what might work.

Looking back at the beach, Dipper took in the group of people who had gathered, who were wondering if their help may be needed while watching a curious drama playing out with two fancily-dressed kids in the water. Quickly he sloshed back the two steps out of the water, and he picked a group of three college-aged girls who looked on with concern. Wiping his face quickly with a sleeve of his jacket, he pulled out his phone with his other hand and politely asked one of the young women to please hold the phone for him. She took it, and he wordlessly turned back into the river.

He walked in and turned to stand beside his sister. He looked down, and was filled with both misery and joy. She was the love of his life! Regardless of their relationship, he would be there for her. He would prove that nothing would keep him from him caring about her. He wanted to show her that her problems were his problems. He would do _anything_ for her.

Mabel wondered what Dipper was doing just standing there beside her, facing the shore. Glumly, she looked up.

Dipper gave Mabel a huge stupid smile, threw a jaunty wave with one hand and a “thumbs up” with the other, then proceeded to fall straight back into the river.

It was a ludicrous sight, cartoonishly executed. And it was completely out of character for Dipper. Mabel was unable to maintain the hardness of her heart after such a brilliant display of silliness. She screamed with shock and delight as Dipper’s back struck the water with a great smack, and she was hit in the face with a splash of water.

Dipper came up sputtering, having inhaled a bit of water. He had no sooner managed to open his eyes when another wall of water was coming at his face, this time courtesy of Mabel’s hands. Instantly they were splashing each other furiously, shouting and shrieking as they fought to see who could get the other to submit. Mabel lunged and pushed Dipper back, but he held on to her shoulder and pulled her down completely underwater with him. They came back up laughing and coughing.

Only a few yards away, concerned Samaritans had become cheering spectators. Everyone who had gathered was now applauding as the young couple dragged themselves sheepishly out of the river. Some of them were still worried and asked Mabel if she was fine now, while others congratulated Dipper on his unorthodox way of cheering up his (assumed) girlfriend. Dipper retrieved his phone, and was informed that the college girl hadn’t just held it for him, she had videoed the entire scene using his phone. She had thought that it might be a memory he would want to keep, regardless of how it had turned out. Dipper thanked her profusely.

A few moments later, Mabel shook herself like a dog, and called out to everyone loudly, “Well, _that_ was fun!” Then turning to Dipper, she yelled with a laugh, “Let’s _never_ do that again!” Everyone laughed, but only Dipper and Mabel knew how much they really didn’t ever want to go through that again.

* * *

For a citizen of Portland, out after midnight in the downtown core, the twins must have been a strange sight. It was rare to see a pair of young teens, dressed for the theater, but soaked to the skin and laughing virtually non-stop. Mabel had lost one of her shoes in the river, and was holding the remaining shoe. As they belatedly realized the usefulness of having that single shoe, they dissolved into more hysterics. They also repeatedly played back the video of their misadventure in the river, and lost it every time they came to the ridiculous expression on Dipper’s face before he took the plunge. They needed forty minutes to walk what should have been a twenty minute trip to the Hilton.

They tried to hold their faces still and look dignified as they strode across the lobby to the elevators, past the concierge’s desk. Their hair was plastered haphazardly, their feet made squishing noises, and Dipper’s heavier clothes were dripping across the carpet. The man behind the desk recognized them as guests, rolled his eyes, and went back to his computer. Mabel’s stifled laugh burst through her closed lips as the elevator door closed.

After they got to their room, they were almost laughed out. Mabel was going to do a face-plant on her bed, but Dipper caught her and pushed her to the bathroom instead, telling her she had to get out of her wet clothes and dry off, first.

Mabel decided to take a quick hot shower: the chill of the wet dress had seeped into her bones. Her momentary funk at the waterfront was completely forgotten.

Wow, Dipper thought to himself after he closed the bathroom door, he couldn’t believe how intensely he felt for Mabel. Actually, the love he felt for her was exactly the same, he realized, he simply had now allowed himself to accept it. But he realized the impact of accepting it. He would always long for her. It didn’t matter where their lives took them, what people they met, to whom they married, or anything: his heart was hers. Only hers. It would be very lonely if he had to face life without her.

Dipper heard the shower and decided to take the opportunity to get his own wet clothes off. He peeled off everything, grabbed a towel, and tried to buff some warmth into his body. He thought he might also take a shower, so he took the other bathrobe and wrapped it around himself.

He went through much of the same questioning that (unknown to him) Mabel had gone through. Was he wrong, falling in love with his sister? Should he even be thinking about her, given how he could never act on his feelings? And even if he could choose to, what would Mabel think of him? She’d already called him a “perv” that evening: knowing this would only make it too true.

Lost in thought, sitting on the edge of his bed, Dipper hadn’t heard the shower turn off. He was startled when Mabel opened the door to the bathroom, wrapped in her own matching bathrobe.

“Aren’t these all soft and comfy?” she enthused, and sat down to her brother’s left. Tugging at Dipper’s collar, she beamed “Still twins!”

“Yeah,” Dipper replied with a smile, poking her back.

Mabel paused, then said, “Dip, I don’t care about some of the things that happened today. I want to say that this has been the greatest day we could have possibly had! Happy birthday, and thanks for being my brother.”

“Thanks, big sis!” he smiled back, and raised his right fist across his body toward Mabel. Mabel fistbumped her left fist back at him.

Instead of pulling back, they both just kind of pressed them together for a long moment. Their shoulders rested together, and they fondly looked sideways into each other’s faces.

Mabel smile widened. “Awkward sibling hug?”

Dipper’s smile widened as well. “Awkward sibling hug!”

They put their arms around each other, squeezed, and in unison, said “Pat! Pat!” as they tapped each other’s back. They relaxed and laughed, then allowed themselves to naturally melt into a long genuine hug. It was an embrace of familial affection and trust, of love between two people are don’t have to be “in love”, perfectly appropriate for a close brother and sister to share.

The close contact, though, was tugging on Dipper’s feelings for Mabel. He closed his eyes and pulled her to himself a bit tighter, feeling the touch of her hair on his face. _God, I wish that I could hold you like this every day,_ he thought to himself. _What I wouldn’t do for that!_ He breathed in, and released a satisfied sigh. “I love you, Mabel.”

Dipper’s eyes snapped open. He heard that last sentence in his ears. He had spoken out loud!

Instantly his body stiffened as he felt Mabel tense at the short statement. In a panic, he pulled back from Mabel. She pulled back too and they looked at each other. Then Dipper wanted to look anywhere _but_ Mabel, and was trying to think of some explanation, some excuse that would make sense. “Umm … I didn’t mean … Uhh … That’s not the way …”.

Mabel took her hand and swiftly smacked it to Dipper’s mouth. It took him a few seconds to stop trying to speak, and he forced himself to look at her face.

Mabel didn’t care what he meant, not anymore! She had to tell him anyway.

“Dipper … I … I love you too!” she whispered back. After a moment, she lowered her hand back to rest on Dipper’s leg.

The twins just stared at each other, motionless. Both were waiting to see if the other meant “love” the way both so desperately wanted to hear from the other. After an eternity of neither of them speaking, and barely breathing, Dipper said softly, “Mabel … unless you say something … I want … I want to kiss you now.”

Mabel dove forward and pressed her lips to Dipper’s, then threw her arms around his upper back and head as she pulled him to her. Dipper responded slowly but eagerly, drawing his arms around her lower back and up to her neck. They eventually broke the kiss and looked into each other’s wide eyes.

“Sorry, I wanted to make sure I didn’t say something,” she smiled at Dipper, a bit out of breath. He chuckled back, as their lips melted together again.

* * *


	7. Lending Each Other a Hand

**Notes for the Chapter:**

> NSFW content to follow

* * *

It was after one in the morning by then, but for the Pines twins, they were no longer feeling tired at all. It was like they had tapped into an oil well: the pressure was released, and their passion started to erupt.

Neither of the twins were very experienced with kissing: they each only had kissed one other person, and both of those were innocent, closed-mouth smooches. Now with the feelings of long-suppressed love urging them on, Mabel and Dipper wanted to figure out how to make kissing more pleasurable. Both knew about French kissing, but neither had tried it.

Mabel opened her mouth first, silently encouraging Dipper to try it, too. Soon they were wrestling their tongues together like pros, while their hands rubbed up and down the backs and necks of their partners. Their bodies were pressed together as tightly as their lips, though still seated awkwardly on the end of Dipper’s bed.

They broke apart, both gasping for breath.

“Wow!” panted Mabel. “That’s _really_ nice! That feels ... so _good!_ ”

Dipper was also in awe. “Everything about you is wonderful … I love you, Mabel!”

Mabel shivered with delight hearing that. She planted another urgent kiss on his lips. “That means I love you, too!”

They rested their foreheads together. Dipper ran his hand through Mabel’s hair and caressed her face, and she hummed happily. They stared into each other’s eyes again.

Suddenly Dipper was uncertain. “Mabel? Are we … is this … okay?”

“I don’t know,” Mabel replied quietly, looking down. “I know we’re not supposed to do this.” She looked back up to his eyes. “I’m not supposed to _feel_ this way. But I _do!_ ”

“I do, too!” Dipper said with certainty. “I think I’ve felt this way a long time, but I just didn’t realize it.”

Mabel shifted, backing away enough to pull her right foot up onto the bed and rotate her body to face Dipper more comfortably, but kept her arms firmly around Dipper’s neck and back. “So when did you realize it?” she asked him.

“Just tonight,” he told her. “When we were in the river at the waterfront. When I was trying to make you get up.”

Mabel’s expression turned stricken. “When you were crying! I completely forgot about that! I’m so sorry!” She pulled his head towards her and kissed Dipper’s forehead.

“It’s okay. Really! If you hadn’t been in that state I might never have realized how I feel about you.” He kissed her lips gently. “What about you? When did you see this?”

“Oh, I was _way_ ahead of you!” Mabel said proudly. “I had it all figured out way back … to this morning!”

Dipper smiled at the revelation that they would both discover their love on the same day, then thought a little more about what Mabel had said. Then his eyes widened, and his mouth formed a small “o”. “Wait a minute,” he said slowly, then his smile started to return. “In the _shower_ , this morning?” he asked slyly.

Mabel’s hand flew to her mouth as her eyes grew wide with embarrassment. “You _did_ hear me!” she cried in a hoarse whisper. “What did you hear?”

“That you had a really great time, mostly!” Dipper retorted, as he turned his body as Mabel did to make himself more comfortable. Mabel blushed, and Dipper grinned at her discomfort. “This serves you right, after all the grief you gave me today.”

“Oh, shut up!” Mabel shot back, forcing the issue by leaning forward and occupying Dipper’s mouth with her own.

Mabel was even less inhibited now. Knowing that Dipper had heard her in the heat of her greatest passion, made her feel even hotter. She wanted to feel more of Dipper, to feel the comfort of the touch of his body to hers. But the way they were seated on the bed, their legs were keeping their bodies from pressing together, and they were both leaning forward uncomfortably.

She first maneuvered her hands to Dipper’s chest. Then with the speed of a cat, Mabel pushed up with her legs and forward with her arms, shoving Dipper down and rolling him over so that he was on his back, and Mabel was now laying on his chest. Though Dipper’s eyes grew wide and he grunted out amused alarm, their lips remained locked. Mabel groaned with satisfaction as she started getting comfortable on top of her brother.

The closeness of the embrace, the weight of their bodies together, caused the twins to more fully feel the impact their new relationship, of what they had been missing all this time.  They reduced the frenetic speed of their kiss, pressing their mouths harder against one another, all the while holding each other tighter and tighter. They finally ended up with their cheeks pressed together and squeezing each other together as hard as they could, eyes moist, whispering “I love you” into the other’s ear over and over again.

Dipper decided that his questions about the morality of their feelings could be set aside for now. This felt too good, for both of them, to question this now. He knew his love for Mabel was genuine, and he wanted to make sure she knew it.

Mabel was even more committed. As they laid tight in each other’s arms, she silently vowed that Dipper would be her first lover. She had no reservations. She could imagine no one else who she would want to give herself to. She didn’t care when or where, but she knew that he would complete her.

* * *

The intensity of the moment passed.  Mabel relaxed her grip, and kissed Dipper’s neck.

Dipper continued to hold on to Mabel tightly, but for other reasons now. “I don’t want to break the mood,” Dipper said smiling, “but I think we’re about to fall off the bed.”

Mabel lifted her head and looked around. Sure enough, when she had pushed Dipper down, he had rolled off to one side of the bed, and because of where he was sitting, his feet were still on the floor over the end. And as they were in the middle of the squeeze hug, Mabel hadn’t noticed they were shifting further down to the corner of the mattress.

As Mabel started to get up off of Dipper, he became aware of how worked up all this had made him. He had been filled with love, wonder, and joy: he had not thought of anything specifically sexual. But his body obviously had been observing what was going on. His penis was fully erect and ready, and as Mabel’s weight lifted up, the evidence of his arousal beneath the bathrobe was plain to both of them.

Dipper’s reaction was to again be embarrassed and remorseful. For all they had just done, he hadn’t even been thinking of what more they _could_ do, but the tent pole beneath the robe indicated that he  _had_ been. He was positive that Mabel would be grossed out, and he had promised her it wouldn’t happen again! He sat up quickly and tried to push it back down, hanging his head shamefully.

Remembering his meltdown at the museum, and knowing that this was a touchy thing for Dipper, she crouched on the bed beside him and grasped his hands, pulling them away. “No, it’s okay!” she said softly, looking at Dipper’s face instead of his crotch. “I don’t mind!” she continued, squeezing his hands.

Dipper turned to look into Mabel’s eyes. It _was_ okay! He couldn’t believe that she wasn’t disgusted by him. Fleetingly, he thought about how a sister was supposed to feel about her brother, and then he accepted it again. He didn’t want to ruin the moment.

Mabel leaned forward and kissed Dipper softly, twice, then a third time. Then she backed off an inch. She knew she was ready to go further.

“Dipper,” she asked gently, “can I … see it?” lowering her eyes down then back up again quickly.

Dipper swallowed. This was going very quickly, far more so than he could have expected, had he even ever expected any of this to happen. But for the life of him, he could find no reason to object to her request. He nodded imperceptibly, and managed to breathe out “… ‘kay!”

Mabel slowly got up off the bed, still holding Dipper’s hands. He was still seated on the corner of the bed, so she gently tugged him to his feet and guided him over to the middle, where she sat him back down again. Putting a knee on the mattress, she pulled Dipper’s arms apart and pushed him back a bit further, then let him go so that he was reclined back with his elbows supporting his upper body. Mabel looked down and again saw the protrusion beneath his robe, and felt a fluttering sensation in her abdomen.

Getting back off the bed, Mabel stepped in front of Dipper’s legs and got down on her knees. She wanted to get a good look at him. She had vague memories of bathing with Dipper as a small child, but this would be the first time she would see him like this, and she wanted to remember every detail.

She reached up and touched the knot holding the bathrobe closed, then as she pulled the knot apart, she heard Dipper’s sharp intake of breath. She looked up and loved the look of awe, mixed with stark terror, on his face. The knot now loosened, she lifted one side of the robe off, exposing Dipper’s left side completely. Mabel gazed lovingly at Dipper’s almost hairless chest, and her eyes moved to his bare hip and upper thigh. She ran the tips of her fingers up his leg and over the hip, up to his waist and chest. Dipper tensed and hissed several times, the tension and his ticklishness (now deliciously uncomfortable) combining to overwhelm him. Mabel’s smile widened, knowing that she was making Dipper feel good.

Slowly, she lifted the other side of the robe off, now fully seeing her brother’s naked body. She stared in wonder at Dipper’s penis. It was about four or five inches long, pointed straight up. It was jerking slightly, obviously in tune with his pounding heartbeat. It was uncircumcised, but the skin at the tip was slightly open, and a drop of clear fluid was forming there. The penis was smooth, and the sack at its base was a bit wrinkly and nestled tight, right beneath it, with just a bit of hair. He also had some soft, fuzzy hair at the base of his penis. She thought it was all beautiful.

Mabel’s right hand moved back down from Dipper’s chest to the newly revealed organ, making Dipper squirm. Agonizingly slowly, she ran a finger lightly up the length of the shaft on one side, then back down the other side. She repeated the process in reverse with another finger. Dipper’s breathing grew labored.

Mabel somehow had an instinctive knowledge of how a penis should be handled. Her left fingers gently caressed his scrotum, while her right hand closed around the shaft, marveling at the heat of it, and how soft, yet hard, it was.  She loved its shape and smoothness. She wanted to see the tip a bit better, so she gripped a bit and pulled down slightly.

Dipper had been hovering on the edge for several moments now. Mabel’s examination had been exquisite torture. Masturbation was one thing, having the girl of his dreams touching him was quite another. And now, one jack downward by his sister on his penis, and he was gone. His hips thrust upwards, and he gasped out “Ma … Mabel!”, then his body went tense and he winced loudly.

Eyes wide, Mabel felt Dipper’s testicles pull tight. His penis throbbed hard, then she watched awestruck as a long rope of milky semen fired out into the air. It hadn’t even landed on his leg and robe when another spewed out: it had less force and splattered on her left hand. She watched amazed as his penis continued jumping in her hand and more semen pumped out the tip, over the shaft, and down over her thumb and fingers. His anguished cries sounded more like pain than pleasure. She had no idea a boy’s orgasm was like this!

Soon enough Dipper’s premature climax was finished. He struggled to regain his breath and composure. He had just blown his load after a grand total of fifteen seconds of actual stimulation. He collapsed onto his back, hands over his eyes and forehead in fatigue and shame.

Mabel didn’t share his negative mood. “Wow!” she enthused. “That was amazing!” She examined her wet and sticky hands, sniffing experimentally. “Pretty messy, though! Do you do that all the time? How do you keep from getting it all over the place?” as she found a towel she had used to dry her hair and began wiping up the semen.

Her nonplussed mood surprised Dipper. He thought she’d be disappointed in him. “Uhh, I … yeah,” he stammered. “That’s the way it goes. That was a …” he blushed, “a pretty strong one, though.” Mabel smiled, pleased. “And usually,” Dipper blushed again, “I use a bunch of tissue, or toilet paper … Keeps things from getting messy.” He thought it odd that he had just ejaculated all over himself and was now completely exposing himself in front of his sister, but he still blushed when discussing his masturbatory history.

Then he figured out that she didn’t know boys took a while to recover after an orgasm. Mabel was using her towel to clean up his penis and groin of the mess, and he noted that it was already beginning to go flaccid.

“Yeah, so … I’m going to be kind of useless for a while,” Dipper said sadly, as he took the towel from Mabel and finished wiping up.

Mabel looked concerned. “I didn’t hurt it, did I? It sounded like I was killing you!”

“No No! It was really, really good!” Dipper reassured her. “But when a guy comes … it kind of goes soft whether he wants it to or not. It takes a while to be able to do anything again.”

Mabel looked at him craftily. “How long?” she asked.

Dipper gestured helplessly. “I don’t know, I never put a stopwatch on it!” he protested.

“Well, then,” she said softly, “you have time on your hands for other things? You’re not _completely_ useless, right?”

The fog over Dipper’s brain lifted, and he realized her innuendo was right. He could do things for Mabel, as she had done for him, and his penis wasn’t required for any of it.

* * *

He raised himself back up to a sitting position while Mabel sat down beside him, pushing the robe off his shoulders and arms, back down to the bed. He felt vulnerable, yet so comfortable, being completely naked in front of his sister.

Their lips found each other again, and their arms found each other’s bodies. Mabel explored Dipper’s bare skin from his neck to his butt and back up again. Dipper’s hands stayed outside Mabel’s robe, as he was still shyly waiting on a sign from Mabel on what she wanted him to do.

Mabel took Dipper’s right arm and grasped his hand. She placed his palm on the exposed part of her chest, just below her neck. Dipper understood that she wanted him to make the next move. Through their kisses, he took a deep breath. He would soon be able to see and touch those perfect breasts.

Dipper slid his hand across to Mabel’s left arm, pushing the robe down over her shoulder. She moaned in his mouth, signalling her approval. His left hand came around to address the knot on her robe, and with a single pull it was loose. Mabel released her hold on Dipper with her left arm, and almost on its own, the robe fell away from the left side of Mabel’s torso. She broke their kiss to pull out her arm from the sleeve and let Dipper see her exposed breast.

It was as beautiful as Dipper had remembered from that morning, through the static cling of the t-shirt. Tentatively, he caressed around its lower edges, and ran his thumb over the nipple. Then he cupped the whole breast and gently squeezed. Mabel cooed satisfied sounds. Gently Dipper lowered the other half of the robe from Mabel’s other shoulder, giving him access to both of her firm mounds. Looking back to Mabel’s face while massaging her, Dipper gently pinched her nipples, eliciting a priceless series of noises, facial expressions, and body tremors from his sister. He let her reactions guide him as to what felt good for her.

As Mabel squirmed around, her robe pooled around her waist, leaving her as naked as Dipper. He was eager to see what awaited him between her legs, but again he waited on Mabel to guide his progress. Instead, still seated beside each other on the end of the bed, the twins pulled each other’s bodies against one other and their kissing resumed. They thrilled in the new sensations of all-over skin-to-skin contact, and their hands roamed freely. Their breathing was growing ragged as the strokes of their fingers and palms moved faster and firmer across each other’s nude bodies.

Suddenly, Mabel snatched Dipper’s right hand and pulled it between her legs. Dipper’s head pulled back from their kissing and they both looked down as Mabel tried to guide Dipper’s fingers to where she wanted him to stimulate. He started to explore her smooth privates, but the angle was wrong: they were partly turned toward one another, so in order to use his fingertips, Dipper had to try to awkwardly twist his wrist, and he wasn’t able to get it turned enough. Mabel tried to help by turning her body to the left, but that left her weirdly sideways to Dipper’s embrace.

Mabel quickly said “Just a second!” and untangled herself. She stood up, allowing Dipper to fully see her body for the first time. She was gorgeous, absolutely beautiful! She had no hair between her legs at all: she would tell Dipper later that she shaved it because it was more comfortable. He reached up to run his fingers down from her breast to her thigh, and he started to stand up as well, but Mabel put her hand on his shoulder to keep him seated. Then she turned around, showing him her firm butt, and slowly sat down on Dipper’s right thigh, pressing her back to his chest, and straddling her feet to either side of his leg. Dipper’s right arm wrapped naturally around her waist, his hand perfectly falling between Mabel’s legs. His other hand reached up to cup her left breast. Mabel tilted her head down to reach Dipper’s mouth, and planted a quick, hard kiss as she pulled his hand to her aching vagina.

Dipper was being given an anatomy lesson by touch alone: he couldn’t see where his fingers were being led. But he was a good student, as he allowed Mabel to guide his fingers to her sensitive spots. His fingers were traced up and down her labia lips, tickling just so. His middle finger was introduced to the inside of her vagina, and it was taught how to stroke the front wall of the tunnel with just the right pressure. She demonstrated how to move her vaginal fluids around to keep everything slick and lubricated. Finally she pressed his fingertip to her clitoris, and showed him how to rub the button to bring her the greatest pleasure. The lesson had no words: Dipper needed only to listen to her noises and feel the reactions in her body as he held her. Quickly he began probing Mabel on his own, and she leaned back against Dipper to slowly drown in the sensations that were building in intensity within her.

As he became more comfortable with what was working for Mabel with his right hand, Dipper started giving more focus to his left. His hand moved over Mabel’s breasts, first one then the other, squeezing and pinching one moment, then light caresses the next. He learned quickly from her reactions what worked and what didn’t, and soon got into a rhythm with both hands that he could feel was building Mabel’s passions with greater and greater urgency.

Mabel was lost, completely at Dipper’s mercy. He couldn’t know how well he was playing her young body, like a fine instrument. Her body and voice reacted to her rapidly growing arousal, and her brain was barely along for the ride.

Just as Dipper was sensing that Mabel was approaching her climax, an idea came to him and he acted before he had time to reconsider it. While keeping up his rubbing of her clitoris with one hand, he grasped Mabel’s left breast in the other, turning the nipple toward him. He arched his neck and sucked the breast hungrily into his mouth, then he quickly reached across her body and used both arms to hug her tightly into himself.

The shock of feeling her brother’s lips and tongue against her nipple, accompanying the magic his fingers were working between her legs, was more than enough to trip Mabel into a thunderous orgasm. Her gasps and groans became a wail that only hinted at the level of pleasure she was feeling. Again and again his fingers and mouth brought her back over the edge. Finally, she had to helplessly flail to Dipper that she needed him to stop. She felt she would die if he didn’t stop. When he finally did, her body lost all its strength, and she sagged forward while she desperately gasped and heaved lungfuls of air.

Mabel’s shifting weight caught Dipper unprepared, and he had to scoot down on the bed to balance her. That put him far enough over the end of the mattress that he could feel himself starting to slide off. He was going to tip forward and drop her on the floor in a moment, and then he was going to sprawl on top of her! Saving her the only way he could, Dipper pulled both his hands free, quickly slid them under her butt, twisted himself out of the way, then unceremoniously heaved her backward up onto the bed just before he landed on the floor with a thud.

Laughter was added to the mix of gasps in Mabel’s breathing. She was splayed out on the bed on top of the haphazardly strewn bathrobes, knees bent, one foot hanging over the edge to the floor. Through her hacking, laughing coughs and deep breathing, she blinked helplessly straight up to the ceiling but managed to ask Dipper if he was okay.

He was more than okay. As soon as he landed on the floor, Dipper had immediately got to his knees and turned to check on Mabel. Directly in front of his face, not a foot away, he gazed upon Mabel’s nether regions, as if she was offering herself for examination. He was fascinated, seeing what he had only felt before. All the folds, flesh of different shades and textures: even the aroma was intriguing to him.

Dipper’s libido was back in force. Mabel’s incredible orgasmic reaction had stirred desires in him that he had never felt this strongly. In another spur-of-the-moment decision, he acted on something he had only seen done in that one brief exposure to a porno video.  Giving Mabel not nearly enough time to recover from her previous climax, he dove his mouth into her vulva, while wrapping his arms securely around her thighs, pinning her down. With one long, single stroke, Dipper ran the tip of his tongue firmly from the opening of her vagina up to her clitoris, pausing there long enough to rub it up and down.

Mabel went from moan to full-on scream in under five seconds. It was a sound indistinguishable from one of terror. Dipper would have thought for sure that he was hurting his sister. But two things told him otherwise: Mabel’s hands had secured to his hair and she was pulling him hard into her crotch, and her legs were holding his head in a death grip. Dipper hoped like heck that security didn’t come pounding on the door. He couldn’t see or even move his head, so he just blocked out the pain from the roots of his hair and started flicking his tongue again, while quickly sliding his hands up her body to find Mabel’s nipples and give them a pinch each.

Another orgasm smashed down on Mabel, hard on the heels of the first caused by Dipper’s tongue.  She had just been arching her back and stretching her head back through the first one. She let out a strangled screech, and convulsed forward to nearly a fetal position as she rode through the frenzy of her come.  

After what seemed an eternity, she came close to passing out from simple lack of oxygen. Her quick gasps were not keeping up with the needs of her body in such an excited state. The only thing that prevented it was that Dipper had also run out of breath, but he was literally unable to get his face free. Having to abandon pleasing Mabel, he had to struggle to pull his head back, and grabbed Mabel’s hands to force her fingers out of his hair. They both collapsed beside one another on the bed to catch their breath.

“Oh my … God, Dipper!” Mabel panted. “I … love you … so much!” as she reached a hand out to her brother.

Dipper took her hand and panted back “I love you too!” then crawled across the bed to snuggle up to his twin. He held her close, stroking his hands all over her body and kissing every patch of skin he could reach between gasps of air. His leg rubbed up and down on hers. He was very fired up now, and very aware of his now-hard penis pushing against Mabel’s hip.

She could feel it too, and decided that now was the time. He had been gloriously wonderful to her, and knew the night could not be complete unless they completed each other. She was absolutely determined that she wanted him inside her _now!_

* * *


	8. Shut Up, Nerd!

**Notes for the Chapter:**

> NSFW content to follow.

* * *

Mabel took Dipper’s face in her hands as he was kissing her neck. She brought it up to hers and they kissed deeply, then she broke the kiss slowly and looked directly into his eyes. “I need you to make love to me!” she said quietly, but firmly.

Most boys would, of course, immediately scramble between a girl’s legs if they heard those words. As had been already established, though, Dipper was not most boys.

His eyes widened, and he swallowed. Even with all that had just happened, what they had already explored together, the suggestion that they “go all the way” stopped him in his tracks. He hadn’t imagined when he awoke that morning that he might no longer be a virgin before the end of the day, let alone that the girl that he would first have sex with would be his sister! He couldn’t just go along with Mabel’s plea: shouldn’t they talk about this? He was positive he was in love with her, but still. There would be no going back to the way things were. There would be no way to unring this bell.

“Mabel … wait … are you sure … I’m just …” Dipper stammered.

Mabel gazed in his eyes. “Yes, Dipper, I’m sure. I made up my mind a while back,” not mentioning that “a while” was less than a half hour previous.

“But … you could get pregnant! We haven’t got anything for protection!” Dipper was aware that Mabel had started her periods earlier that year, and what that could mean to a girl having unprotected sex.

“I just finished my period three days ago. I’m perfectly safe, Dipper!” Mabel told him quickly.

Dipper had already thought of another objection to be considered. “But … isn’t it supposed to … _hurt_ you the first time? … I don’t want to hurt you!”

Mabel exhaled lightly with impatience. “You mean you don’t want to bust my cherry?” she replied quickly, unbelieving that Dipper wanted to debate this.

“Well … yeah, I guess if … that’s what hurts?” Dipper was not fully educated, but he did have Mabel’s interests in mind.

“Dipper, you know my hairbrush?” Dipper nodded dumbly. “Well, it’s been used for a lot more than brushing hair and as a fake microphone!” Mabel barely waited for Dipper’s expression to register understanding. “It won’t be painful for me.  I _want_ this Dipper! Please!”

There was one card left, and Dipper had to play it. He didn’t want either of them to be regretful. He drew a deep breath.

“Mabel, please … it's  _not_ that I don’t want to do this but … are we _sure_ this is right? I mean … our age, for starters. Are we … are we mature enough to handle this? We might _think_ we are, but do we know? And this … this is …” he struggled to say the next word, but it had to come out. “...  _incest_ … what does that mean for us? Can we ever be in a relationship? I don’t want …” Dipper’s voice cracked, and tears sprang unwittingly from his eyes. “I don’t want you to give up something so important … for someone you can’t be with!” Dipper finished with a sob.

Dipper had confessed to Mabel his biggest fear that he had been thinking about since the waterfront. He was scared that he would spoil Mabel’s life, that he would ruin her chances for a normal life and happiness because he selfishly wanted to indulge in something they may regret. He was scared that she would someday view this night as the rest of the world would view it: an immoral, perverted act between twin brother and sister.

And because he thought he was a responsible, protective brother, he took it upon himself to make sure that he would, on her behalf, consider these consequences to Mabel. He didn’t assume that she would have considered any of these for herself.

Dipper was incorrect. Mabel had thought of these issues all day. She loved how sweet Dipper was, how he so obviously just wanted to do what was best for her, but she had to get through to him. She kissed his eyes, tasting his tears, then backed away so that he could see her face clearly. She still held his face in her hands.

“Dipper … I’m old enough to know that I’m in love with you. I'm mature enough to know that making love will change things between us, but because it’s with someone I’m in love with, it’ll only be better! I know that I love you. And I know _you!_ I _know_ you love me too … I … I can’t _ask_ for more than that! I don’t care that you’re my brother, except that … except that being my brother makes me care about you even more! I don’t _care_ if we can’t be open about ourselves to the world! I don’t care if we can  _never_ be together again! _No one_ can ever be who you are to me! I will never be sorry for _anything_ we do! You want me to save myself? For someone else? Who could I ever choose before you?“

She took an unsteady breath, as tears of her own started to roll down her cheeks. "I want you to be my _first_! I want to be _your_ first! I … I’m _sure_ , Dipper! I’ve _never_ been so sure of anything!” Her voice was starting to break, as she became more desperate to find words to match her emotions.

It was the longest speech Dipper could ever recall Mabel making. He was touched and surprised to hear such confidence and conviction from her. He saw that she _had_ thought this through, _more_ than he had.

Mabel paused, fearing the answer to her next question. “Are you sure _you_ want to do this?”

Dipper also paused, wiping his face with his hand. “I don’t know that I _was_ sure or not,” looking down as he replied, then looked back into Mabel’s eyes. “But I _am_ sure now.”

They both closed their eyes as Mabel drew his face to hers, and they sealed their bargain with a long, gentle, loving kiss.

* * *

After they had agreed that they would consummate their relationship, Dipper didn’t feel that the proper way to move forward would be to just climb on and start fucking. At any rate, impromptu debates about the pros and cons of entering into an incestuous relationship can put a damper on one’s sexual readiness. Given the half-mast status of his penis, it wouldn’t have been possible for Dipper to perform at that moment, even if he’d wanted to.

Mabel had also noticed the lack of firmness in the organ that was pressed up against her hip as they held each other. A mischievous twinkle was growing back into her eye after the seriousness of their talk. She motioned down with her head. “Is he okay?” she asked, smiling sincerely.

Dipper smiled back at the assignment of gender to his penis. “Yeah, I guess I wasn’t feeling very sexy for a few minutes, there,” he explained. “I’m sure we can get him going again!” as he started snuggling back up to her body.

She pushed back against his chest. “Oh, no! You’ve been ignoring him, haven’t you?” she said with faux shock and outrage. Dipper was baffled, but amused. Mabel pushed harder and rolled him on his back. “I will not _stand_ for this! I will be … his _hero!_ ” as she quickly crawled down over his hip. Mabel had decided that _if Dipper could just launch a sneak attack of oral sex on me, well, two can play at that game!_

Dipper barely had time to register what Mabel was doing as she engulfed his partially-erect penis into her mouth. Mabel would never have believed that she could ever have done this before that night. With no inhibition left, she was willing to do anything at all for her brother. With one hand she held the base of his penis, and with the other she cupped and tickled his testicles. She knew that teeth would probably not be appreciated, so she hid them as best she could and pulled her mouth back, sucking as she slid her lips and tongue over the sensitive skin, then kissed the tip and lowered her mouth back down. By the third time down, she already felt that Dipper was harder and thicker. By the fifth time, it had swelled to the point that she could no longer get her mouth all the way down to the base. Mabel stopped with her mouth full, and glanced up to see Dipper’s expression.

For his part, Dipper had never seen or felt anything that turned him on so much. The sensations of Mabel’s mouth on his penis, combined with the awe of what she was doing for him, aroused him faster than he could fathom. His face must have conveyed this well, because the edges of Mabel’s mouth curled up. Then she slowly backed off, suctioning and caressing with her tongue the entire way, until she pulled all the way off with a wet smack. She kissed and licked it a few more times, as Dipper stroked her hair and gently palmed her cheek, pulling slightly to get her to bring herself up to his face. He could feel how quickly his arousal was building, and he didn’t want to come again, not yet. Keeping up the massaging of his testes and with a sly smile, Mabel kissed her way slowly up his body until he finally had to pull her up by her armpits so that he could grab her head and kiss her on the mouth fiercely.

“You are going to be his hero _forever!_ ” Dipper breathed between kisses.

Mabel moaned into his mouth, shifting herself around to lay on her side next to Dipper. She was grinding herself into his right hip, working one leg beneath him and the other on top, while she reached across to his opposite shoulder. She wanted Dipper so badly now. She was about to grab her brother and pull him on top of her.

Dipper had other plans. Mabel may have said that she didn’t worry about it hurting for her on her first time, but he would be damned if he wouldn’t try his best to make sure that didn’t happen. Simple physics said that if Mabel were on top, she would be able to control how deep and how fast her penetration happened. Also, he knew from his own experience with masturbation that he had a better chance of lasting before his orgasm if he was on his back.

So instead of waiting for Mabel to try to pull him over, Dipper stayed on his back where he was and pulled Mabel up onto himself.  She pursed her lips into an “ooooh” face, understanding what Dipper wanted.

Straddling his waist with her legs, Mabel allowed Dipper to pull her down to him. She settled her weight down on Dipper’s chest and they shared in a long, deep kiss, holding each other tightly. Coming up for air, Mabel wiped her hair from Dipper’s face and looked down into his eyes. A mixture of nerves and anticipation filled her. “You ready?” she asked him quietly.

Dipper was trying to be cooler than he felt, but his brain was not cooperating. All he could come up with was a small “Yeah!”

Mabel sat up, rocking herself on his thighs below his hard penis. With her left hand, she reached down to probe herself, verifying that she was wet, and gave herself a quick pinch on her clitoris. With her right hand, she stroked Dipper’s penis up and down slowly, mentally preparing herself for it to be inside her in a few moments. His hands played across her thighs, hips, and waist, not wanting to rush her. She smiled lovingly. Because Dipper had insisted on her being on top, it was a sign of how much he trusted her, as it put her in control of their coupling.

She moved forward and raised her body up, and rubbed Dipper’s penis against the front of her slit, down over her clitoris and back up again. New shivers of pleasure ran through both of them, as Mabel lightly masturbated on Dipper’s tip.

Finally, she was ready. Mabel held Dipper’s penis to the opening of her vagina, and they both watched and felt the head slide snugly inside. They both inhaled sharply, then together they looked from their merging crotches to each other’s faces. And together, they whispered, “I love you!” and then smiled. _Twins!_

The smile stayed on Mabel’s face as she closed her eyes and craned her neck up, resting her hands on Dipper’s shoulders. Then, slowly, she let down her weight, forcing Dipper’s penis into herself. She was aware of a whole new class of pleasure as he slid past nerve endings that had never been touched before. There was a stretching sensation, but nothing that she would ever describe as pain.

Dipper was watching his penis disappear into his sister. He could feel the wonderful, moist warmth surrounding it. She was tight, and his foreskin was being pulled down over the sensitive head as it went in, which only added to the stimulation. He couldn’t stop himself from slowly raising his hips as Mabel bore down.

Finally, their pubic bones met, their virginities gone. Mabel’s breathing was shallow and quick, her body quivering with thrilling new feelings. She was now pushing down hard, as Dipper was pushing up just as hard while pulling on her hips, making tiny thrusts into her, trying to get inside even deeper.

Dipper felt a boiling sensation in his testicles, and was aware that he could come any second, so he relaxed his pelvis. Mabel also stopped pushing and bent down on her brother with wide-eyed wonder. “Oh my God!” she breathed. “Oh … my … God!”

“You’re incredible!” Dipper panted back, unconsciously thrusting his hips again, sending another thrill into his sister. “Are you okay?”

“Oh God yes!” she gasped back. “You feel so good! I love you so much!” She reached down and gave Dipper a quick, hard kiss on the mouth.

Dipper caressed Mabel’s face. “I love you too!” he replied with an excited smile. Then he swiftly slid his other hand from Mabel’s hip to underneath her breast, raised his head from the bed, and tried to inhale as much breast as he could while rolling her nipple around on his tongue.

Mabel cried out, almost softly, as Dipper’s mouth and penis combined to send even more electricity through her senses. Automatically, her hips began moving, as she and Dipper began a gentle rhythm together.

Dipper experimented with pleasuring Mabel’s breasts. He rolled her nipple with his tongue, kneaded with his hands, kissed everywhere, and gently sucked. He tried to duplicate Mabel’s sucking technique on his penis, keeping his teeth under his lips, but as he pulled off to switch to the other breast he slipped and the nipple grazed his teeth. Mabel gasped loudly and tensed.

“I’m sorry,” Dipper apologized. “I didn’t …”

“ _No_!” Mabel looked back at him. “Do that _again!_ ” Dipper happily spent the next few minutes adding gentle bites and chewing on nipples to the list of ways to add pleasure to their sex play.

The twins were both trying to not lose control, wordlessly agreeing to try to make this moment last as long as they could. But the speed of the movement of their hips was accelerating, and their bodies were coated in a film of sweat from the exertion of their efforts.

When Dipper’s teeth made an especially sweet impact on her left nipple, Mabel could not hold back any longer. She groaned loudly, sat straight up to push Dipper into her as far as possible, and started grinding with abandon. She could feel her orgasm was just below the surface, and she wanted Dipper to come with her.

Dipper could not imagine a sight more erotic than what he was seeing. His beautiful sister, face flush with passion, was pounding and gyrating her body onto him. He could see his penis appear, then disappear back inside her as she pushed down to meet his upward thrusts. He could see her gorgeous breasts bouncing perfectly to the rhythm of their movements.

He was getting close to his climax again, and he knew he couldn’t stop it this time. By now Dipper knew Mabel’s noises and knew that she wasn’t close enough, that at this pace he would come before she had an orgasm. Through his frenzy, he saw an opportunity to help her. While increasing the pace of his own pelvis, he let go of her hips and reached down with his thumb to rub Mabel’s clitoris while pinching hard on one of her nipples.

Mabel convulsed and shuddered. She let loose a guttural, strangled scream as Dipper attacked her three most erogenous zones at the same time.

Dipper couldn’t hold on, he was over the brink. The pressure built to an agonizing crescendo, then burst in the most intense release of pleasure in his life. He practically shouted through his clenched teeth as he felt his semen fill his sister.

Her orgasm was just hitting when Mabel felt the first pulse of her brother’s penis and sensed his ejaculation firing on her cervix. Overwhelmed, she flung herself forward onto Dipper as it felt like her insides had exploded in joy. She buried her face in his neck, screaming and crying. Her body was quivering, every muscle dedicated to trying to squeeze Dipper and herself together into one body, one soul. Dipper was squeezing back desperately, sharing in the intensity of their love.

* * *

They finally began to come down from their passionate high. Dipper’s lungs realized they hadn’t inhaled in some time, and he took breath after breath to get oxygen to his brain. Mabel was also panting heavily, as she relaxed her grip and just lay exhausted on Dipper’s heaving chest.

After they had mostly recovered, Mabel raised her head, and Dipper turned his to her.

Dipper gazed at his sister in wonder. She was everything to him! _Partner in mischief. Mystery Twin. Best friend. Soul mate. Love of my life._

Mabel stared smiling tiredly at her brother. She loved every bit of him. She didn’t think she could be happier, and she adored making him happy, too. _Best brother ever!_

“I love you so much!” they said together. They laughed softly, resting their foreheads together.

Mabel thought she was getting heavy on Dipper, so she slid off and they curled up together on their sides, stroking each other slowly and kissing deeply and lovingly. She tried to stifle a yawn, but when Dipper also yawned, hers emerged as well.

“You tired, too?” she asked, stroking hair from his face.

“Yeah. It’s been a long day,” Dipper replied quietly. “We need to clean up before we go to sleep.”

Mabel flopped over and spooned in to Dipper, pulling his arm around her. “Just a few more minutes of snuggling. Everyone needs snuggle time on their birthday. It’s a new birthday rule I’ve just decided on.” Mabel’s voice was a dreamy sing-song.

“Technically, it’s not our birthday anymore, goofball,” Dipper said, nuzzling the back of Mabel’s neck, intertwining his legs into hers, and letting his hands fall easily to her breasts. “It’s Sunday,” he said drowsily.

“Shut up, nerd,” replied Mabel smiling, her eyes closed.

* * *


	9. Love Shack, Baby

* * *

The phone between the beds was ringing.

Dipper dragged himself out from sleep to find himself and Mabel sprawled naked on his bed. They had fallen asleep without getting under a sheet, and had stayed huddled together. Where their skin was pressed together, they were sticky with sweat and their spent juices, while Dipper’s backside was cold. He scrambled over Mabel to get to the phone, producing a muffled complaint from her as he fumbled with the handset. “Hello?” he answered blearily, his voice cracked and hoarse.

“Whoa! Dude! Did I wake you up?” came Soos’ unmistakable voice at the other end of the line.

“Yeah, Soos … Why are you …” Dipper’s eyes finally focused on the clock beside the phone. 11:50. Check out time was Noon!

“Oh, crap!” he exclaimed. “We slept in! Mabel!!” he called. Mabel heard the urgency in Dipper’s voice and forced her head up in confusion. “Where are you, Soos?” Dipper asked hurriedly.

Soos was happy as usual, but concerned about the kids getting in trouble. “Downstairs, in the lobby. Nice place you’re stayin’ in! Ya know, Dude, I can come up and help you get your stuff ready …”

“ _No!_ ” Dipper shouted into the phone, in a panic as he looked at his and Mabel’s thoroughly naked, thoroughly sexed bodies. Mabel was awake now, and looked at him in confusion. He lowered his voice somewhat. “No, it’s okay, Soos, _don’t come up_ ,” he emphasized so Mabel would understand. “We’ll be down as fast as we can!” and he slammed down the phone.

“We’ve got _10 minutes_ , Mabel!” Dipper cried.

It was pandemonium.  Mabel screeched and leapt to the bathroom to quickly try to wash herself with a wet facecloth. Dipper grabbed the soaked, soggy clothes from the bathroom and the floor and stuffed them in one of their suitcases. Into the other suitcase, they tossed everything else. They managed to find clean clothes and put them on, but as they were on the way out the door, they both thought they knew exactly what they looked like: two guilty teenagers who’d just slept together.

Thankfully, they had the elevator to themselves. They had only a few precious moments before its doors would open downstairs. “Mabel?” Dipper asked, “Are we okay?”

Mabel looked surprised. “Of course we are! Why _wouldn’t_ we be!” as she ran her finger over his nose and lips. Her ability to be positive about her life never ceased to amaze Dipper.

“Well, we can’t let on to Soos about … you know … this!”

“I know,” she said confidently, “It’s going to be hard, but we’ll manage.”

The elevator was starting to decelerate for its stop at the ground floor. Dipper leaned forward, and they quickly kissed, breaking apart just as the doors were opening. Soos saw them and waved from across the lobby. The twins headed toward him and the desk for checkout.

“I love you,” said Mabel quietly as they walked, glancing at her brother.

Dipper smiled self-consciously. “I love you, too,” he replied equally quietly, glancing back at his sister.

* * *

The ride in Soos’ truck on the way back to Gravity Falls was awkward. For four hours, the twins had to tell a story as if they had a great time (which they did), without hinting at what they couldn’t let Soos know about. They also had to keep from touching each other or gazing at each other in ways that they hadn’t done before. They didn’t know if they succeeded in fooling Soos or not: they had found out last summer that he was far more insightful than he led on, or sometimes even realized himself. Regardless, he seemed to just be glad to have his little dudes back again.

When they arrived at the Mystery Shack late in the afternoon, Grunkle Stan was busy with a group of tourists. He made eye contact with the twins, but that was it. Thankfully, he didn’t stop to talk to them: if he had gotten a better look at them (or smelled them, for that matter) he may have been suspicious.

Mabel took a shower first and changed into clean clothes again. Dipper waited for her to finish with his own change of clothes. As Mabel was leaving the bathroom, they stopped for a quiet kiss. It was almost a disaster, as Stan had come in from outside to go to his office. They separated barely in time before he came around the corner.

After almost getting caught, both forced themselves to act _normal_ for the remainder of the day. It was agony. All they wanted was to be able to do what young people in love do, and they knew they couldn’t.

Finally that evening after supper, they told Stan they were going to bed. Just as Mabel finished closing the door to their attic room, Dipper grabbed her. Their kiss was passionate, and full of pent-up longing.

Mabel was the first to speak. “I didn’t think it would be _this_ hard!” she whined, holding Dipper’s face.

Dipper agreed. “I’d almost rather we not have to live together, then we wouldn’t have to see each other all the time!” Mabel looked at him with fake anger. “ _Almost_ rather, I said!” Dipper repeated with a smirk, glad Mabel had lightened the mood.

Mabel kissed him again. “Good! Because if we didn’t live together, we wouldn’t be able to do _this_ right now!” With that, Mabel pulled off her sweater, followed immediately by her t-shirt.

Dipper looked nervously at the door, then back to his freshly half-naked lover. “Mabel, this is crazy. We’ll get caught!”

“Not if we’re quiet, we won’t!” Mabel replied, already finished untucking the bottom of Dipper’s t-shirt, then pushing it up over his head.

“Mabel, we’re not quiet! We certainly weren’t last night!” Dipper’s ability to object was already at its end, as he was sliding his hands over her breasts as he said this. Mabel hummed happily.

“Then we’ll have to figure out how to _be_ quiet! Because you are taking me _right … now_!” With that, Mabel sucked on Dipper’s tongue and fumbled with his pants, while Dipper unzipped Mabel’s skirt.

* * *

The kids _did_ learn how to be quiet. They also learned a lot of positions. They had a lot to learn in a short amount of time, as they would be on a bus back to California the next Saturday morning.

Over the next several days (their last week of the summer), Dipper and Mabel found every excuse to find a place alone. A picnic in the woods one day. Exploring caves the next. A swim at a remote pond another day. Each time, they would arrive back much less stressed than when they left.

Then each night, the twins would couple again, basking in the wonders of young love.

* * *

 


	10. Fallout

* * *

Stan noticed the change in their behavior. He’d have to have been an idiot to miss it. The guilty-looking meetup outside the bathroom on Sunday. The long field trips in the days since. Going to bed early each night. Locking eyes and smiling at each other all the time. And just getting along in every way _even better_ than they had before (which was already unnaturally good).

These kids were smart, but apparently they were like most kids: they thought adults were stupid. It was obvious they were experimenting sexually with one another.

Stan had a hidden sensitive side for the twins, but he figured “gruff” would work better for this talk. He had to scare these two now, or they’d get into real trouble when they returned home to their parents and got caught.

Friday evening, after closing the door to business and sending Soos and Wendy home, Stan called Dipper and Mabel into the living room.

“Sit down, you two,” he ordered. “We need to talk!”

Mabel looked nervously at Dipper. Dipper was still working on standing up to his uncle, so he stoically stared back at him. Stan regarded him, silently approved of his toughness, then ploughed ahead.

“You want to tell me what you’ve been doing this week? And what you were probably doing in Portland?” he asked bluntly. Dipper’s eyes widened, and Mabel couldn’t meet his gaze. Neither sibling volunteered to speak.

Stan continued, “Look, I actually don’t know _exactly_ what you’ve been doing, but you’re messing around with each other. Getting way closer than a brother and sister ought to. You think you’re not being obvious, but you’re wrong!” He let that sink in, watching their panic rise. Their silence spoke volumes. If it had not been true, they would certainly have forcefully objected to his innuendo.

After another moment of no response, Stan said, “I can just keep guessing increasingly uncomfortable questions! And you can bet your parents will notice too, and have the same questions!” This suggestion raised the alarm of the kids even higher. Mabel looked like she wanted to cry.

“Or,” Stan paused, “you too can just tell me you’re going to stop this right now, and that it will never happen again!”

Stan had hoped that he could just nip this in the bud, and end their playing around there and then. Make them see that it would be wise to not play with this particular fire. Give them a good scare, a chance to move on without getting punished, and they’ll concern themselves with more normal teenage issues.

Unfortunately, he had no idea how deep Dipper and Mabel were in, until now. Stan saw instantly on their faces that the idea that they stop doing anything with each other was downright horrifying for both of them. They grabbed each other’s hands. The idea sounded even worse to them than their parents finding out!

Son of a bitch! He knew exactly what the issue was.

Stan groaned loudly, turning away in frustration. The kids were too petrified to move. Their uncle turned back towards them. “You might as well fess up to me. I know what your problem is! No point in denying it.”

“Whaa … What?” stammered Dipper.

“That you’re in love with each other?” shot back Stan.

The twins’ grip on each other’s hands grew even tighter. They said nothing.

“Yeah,” Stan sighed. “That’s what I thought.”

* * *

Grunkle Stan finally got the kids talking. He was very uncomfortable with the fact that his niece and nephew were in an underage, incestuous relationship, but he knew they obviously weren’t handling it well on their own, and they needed him. He told them how important it was to discuss this, and he offered to help them determine what they needed to do going forward. The twins eventually agreed that they could trust their great uncle. After the last summer, Dipper’s feelings of betrayal by Stan had been long forgiven. The Pines family stayed up late that evening.

They all agreed that they knew the twins’ parents would _not_ be accepting of this development. Letting them figure it out, like Stan did, would be a recipe for an explosion. Their parents were fully capable of forcibly keeping the twins apart, sending one off to boarding school if necessary. Mabel and Dipper both couldn’t bear risking this fate.

And even if their parents had been willing to accept their relationship, no one else would. If their love became known, they would be shunned by their friends at school, and juicy targets for bullies. No social club would have them. Adults would be judgemental or cruel. And they couldn’t imagine what would happen if the church their parents took them to found out.

Mabel suggested that they could just be more careful, to not let anyone find out. But Dipper pointed out that they _thought_ they were being careful in the past week, and that they would have vastly less room for mistakes in California: there was not wilderness to go to for private field trips, there were people they knew (and those that knew their parents) all around, and they didn’t share the same room in their house like they did at the Shack. Mabel admitted that spending a lot of extra time together in private would be very suspicious. They would surely get caught.

As much as it pained them, they concluded that the twins had to do exactly what Stan had told them they must.

They had to stop.

* * *

It was very late when bags were finished being packed and by the door for the morning’s trip to the bus station.

Grunkle Stan chose to look the other way as the twins sadly took each other’s hands and walked up the stairs to the attic. He couldn’t begrudge them one last night together.

Their lovemaking that night was long and slow, full of cries and tears of both ecstasy and sorrow. Neither of them wanted it to end. Mabel stayed in Dipper’s single bed, and when they finally fell asleep, they were huddled together in each other’s arms.

* * *

The bus ride required a transfer, and it would be late Saturday evening before the kids would be home.

Dipper and Mabel had time to talk about their feelings, about how their love would survive this test, about how they would wait for each other until they were eighteen, and about how then they could run away to be together. It sounded good, neither admitting that they both knew it was unlikely to turn out that way.

They mostly just spent the trip holding hands, kissing, and gazing at one another. It was young love, the first time for each of them. Precious for both, forbidden by everyone else.

They did make one practical plan. They knew that they may have to be able to carry on as just brother and sister in front of everyone, but they _had_ to have a way to let each other know how they were feeling inside. A way that no one would think unusual.  A secret way to say “I love you.”

* * *

Their parents met them at the Oakland bus transit station. There were lots of hugs, mussed hair, height checks, and exclamations of missing one another.

On their arrival at their house, it was well after midnight, and everyone was tired. Bags were dumped, and everyone just headed for their rooms.

Dipper opened the door to his room, Mabel to hers. They were directly across the hall from one another. They looked each other in the eye.

“G’Night, Mabel,” Dipper said, with a small, fond smile.

“Night, Dipper,” Mabel replied, unable to mask a catch in her voice.

They bumped their fists, and held it for a second.

Then, sadly, they backed into their rooms, and closed their doors.

The End

* * *

**Notes for the Chapter:**

> Hope you enjoyed this, this was my first attempt at fan fiction. 
> 
> I’m going to ask that if you want to review the story, please do not “give away” the sad ending. I tried to foreshadow the possibility of everything not working out as they would want, but still I wanted the conclusion of the story to be a bit of a kick in the balls. I’m hoping that not knowing will make the impact to the reader all the greater. Thanks.
> 
> E-o-F


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